differance in heads
 

is a N42 head have higher compression than a P79 and does it have round or square port exaust. does the block from a 75 have flat top or dished pistons

the n42 head has square ports for the exhaust, and would have a higher cr than a stock p79 which has round ports with liners. as for the block part, i believe (dont quote me on this one) is has dished.

Yeah as far as I know. Dished pistons till '81. Then they went to flat top ones.

my 81 NA zx had flat top..

^^Yeah that is what I meant to say. lol They started with flat top in the '81 year.