i have 75pontiac350 with factory trans from 76grand prix.was a runner when pulled,but has a bad crank bearing.i have not seen any build ups on this engin.  

I done alot of them and seen different builds on some sites as well how much power are you wanting out of it.and what is the casting numbers on the heads as well as the block.  

i want good street power around 400HP.they are 6X heads the block is marked in 3 places.the front of the block on pass side is stamped YB.at the back of the blockon top deck is 1096.on pass side back of block 500810. this was a 4BBL engine we changed intake to a 2BBL for local circle track comp.still have 4BBL intake.  

You will need 9.5:1C.R., headers, 600CFM, pocket port the heads and have a 3 angle valve job done on them, have bore .030 over, 2.11/1.77 valves and a good dual plane intake like the performer or the performer RPM from edelbrock.Also you need to get different heads the heads you have are low compression witch only give you a 7.6:1C.R. try to find some heads with 72CC combustion chambers LIKE #13,16,62,48 all have 2.11/1.77 valves and 72cc chambers.  

thanx pontiac4.are all pontiac heads marked the same place as my 6x heads?are the heads you mention pre emissions? will heads from 326,389,400 work.would i be better off buying a Edelbrock PKG. heads,cam intake and carb or stick with the iron.would decking the 6x heads do any good/or waste of money..  

All pontiac heads are marked on the center exhuast port.The heads #16,#62 are from 1968-69 400c.i.,#48 are from 1969 350 h.o., and the #13 are 1970 400c.i. Decking the 6x heads would be a waste of money. Stick with the iron heads and I would also use a lunati streetmaster cam P#07702 witch has a .507 lift I forgot to mention that in the last post and this will get you to your goal.