I am looking at a 83 NA that has been rebuilt. They put in turbo valves,valve springs and pistons. The rings have been sized to the block as well.
I have never heard of this. What should I expect from this?
Is this something that would make the engine better or is this something to run from ? Thanks.

 

I would be careful personally. As an n/a is quite a bit different from a turbo. The n/a has higher compression and the turbo has lower because of the boost. I would do some research if you can on it. Or hopefully somebody can help you out on here. Good luck.

 

Back in the old days they filed the ring gap to get it as close as possible to ensure proper compression only a pro would have done this prolly not your shade tree mech. But what ya got to look out for is that the rings are positioned with the ring gaps in the right place ... Sounds like someone was building a turbo motor and that would mean it has lower compression pistons than a n/a I'm thinking the stock compression on a l28 is 12 or 13 .1 or something like that on a n/a but the turbo piston compression will be considerably lower prolly 8 or 9 maybe depending on the boost level you will run ... I'd do a simple compression test it will let ya know what ya got... Hope this info helps

 

It makes no sense to use an F54/P90a engine with dished pistons as an n/a setup. Dished pistons lower the CR for turbocharged boost.
In essence you have an L28ET turbo engine, without the turbo. It will be very sluggish.