stcrispin

As I begin to knee deep in my 76 (or 77 we never figured that one out!) and I begin to replace more and more parts, I wonder is it advisable to upgrade to "performance" parts? While I'm not looking to build a rocket ship, and am a bit of a purist, I would like to put some teeth in the ol' Z, but I don't want to break it either!

A few other odds and ends..

What do we recommend for oil/gas? I'm assuming you all will say Castrol, but what wieght? and what of octane? Again I'm going to assume regular unleaded with an octane in the low 90's?

What's with the louvres? I kicked mine down the parking lot, they ruin that lovely line running on the rear 1/2 panel.

BoulderZ

Well, here's my thoughts on it. Hopefully others will post, too, as it would be interesting to see the group's preferences.
Your intended restore/modify balance sounds similar to mine. By far the easiest way to bump up your performance is the exhaust, particularly the pre-muffler (pitch it) -back stretch of it.
If you want to add headers to that, most of the comments out there seem to indicate you won't see a huge performance increase for the money (and effort) unless you spend some time/$ working the head, too (cam and associated parts, a little porting/polishing, valve job, etc.). The larger throttle body upgrade might be a nice change if you've done the work above, and would go nicely with a oil/foam filter element (Amsoil) or intake upgrade (K&N for instance).
Just about everyone has great results changing out the many bushings to urethane (some keep rubber in some spots if it's more of a GT application and not just go-fast desire). You can use whatever mix sounds good for your preference, but I'd definitely replace whatever's there now as it's almost certainly dried up/rotten out long ago.
No sense upgrading the parts to go faster without also making sure you can stop the thing, too. Easiest on that is to replace the front calipers with early 80's Toyota 4x4 calipers. Bolts right on, and you've instantly upgraded to a 4-piston front system. Replace the 20+ year old rubber flex lines with nice new braided stainless lines while you're at it. Cheap, and you'll have to bleed the system anyway. Easy as pie. If you want your brakes the next step above that, there are some really nice 4-wheel disc conversion kits now from several vendors. I think I might go that route on mine.
Now that it goes faster and stops better, you might want to add an airdam. The stock valence lets a lot of air under the car, and hence there's a lot of lift, especially of course at higher speed. While it's not truly factory original, it's still a generally forgiven modification even amongst the purists. I went with a fiberglass MSA model with some brake duct openings (and using my brother's design for truly adding ducts to the front brakes). While I really don't personally like 99% of the body kits and appearance mods and wings and that kind of stuff, there are a few pieces that are actually quite functional, and a good airdam seems more than worth it to me.
Depending where you live you may want to do something with the radiator/cooling. Could be as simple as ditching the viscous clutch fan for a nice electric flexalite (or two), or getting a 3 or 4 row upgrade radiator, or going with an aluminum radiator. I'm going with the aluminum and a single flexalite on mine.
Better handling and ride can be had easily with a set of springs (as stiff or cushy as you want), new shocks (Tokico regular or adjustable illumina, etc.), complementary and matched sway bars, and decent tires (don't know if you need or want wheels, up to you). I'm going with MSA springs and bars, the MSA Flashback wheels in 15x7, and Tokico illuminas, urethane bushings (including steering coupler) all around. If you're going to be mostly on the track, maybe you want to think about doing a full coilover conversion.
For oil, I only use Amsoil's full synthetic (series 2000 or whatever the marketing shelf name is these days). I generally follow the temp/viscosity in the FSM, and err a little on the thick side as synthetic doesn't thicken up nearly as badly with low temperatures as regular oil. I aim for 3000 mile change intervals, but it's easier to do it yearly (which is less than 3k for me).
For gas, the FSM says use 91 octane. Guys with thinner head gaskets, or domed pistons, turbos, or anything else that boosts the compression need to run higher octane. Here at altitude, 91 is the highest you can get at typical 3-choices pumps anyway (you don't need as much octane as altitude increases). When I used to live at sea level, I used 93 or 94. At the gas stations I used back then, it was only barely more expensive (less than a dollar or two per tank more at the time), but was actually refined on a completely separate line to a higher spec, so it wasn't just the octane (which would have been fine at 91 anyway), it was also cleaner gas. The usual advice about only going to decent, newer (less sediment in the holding tanks), well-run, clean gas stations with reasonably high inventory turnover of course applies, too. Anyway, that's my 2 cents.
Dave

stcrispin

Wow, that was a great list of advice and parts, it is much appreciated it, I'm going to print it and stick in my repair manual so I can refer back to it.