i am about to get underway with a 400ci sbc for my 82 z/28, i am using low comp pistons,,for pump gas,,,and a 262 comp cams hyd cam,,a set of 1.52 pro magnum roller rockers,,,an edelbrock 2116,,and a 750 vacume holley,,,,i want all this happening under 5500rpm,,an msd,,1/58 headers ,,,2,1/2 exhaust,,,is there anything i can do to the heads to get the larger bore 400 to work well,,,(with these brand new vortec heads i just bought,,) ,,,,,we will be changing the valve springs,,to suite the cam,,,,,and i hear 2.02,,,,1.6 valves are no advantage,,,but that was on a 383 crate motor,,,i read about,,,,will the 4 1/4inch bore need bigger valves ,,,and is there any information out there in support of this,,,,,,
the transmition will be changed to a t700r4 later and a 9inch rear end installed,,,with 3.25.1 gears,,FIRST i want to get the engine up and running,,,and installed,,,the car will not be drag raced,,,i am simlpy re powering the car,,,like it should have been from new,,,please help,,,

 

might want to consider a set of manely pro flows, maybe surface the head or mill it, do some porting, gasket matching, and polishing. i'd mill the valve guides and remove the pull out studs and mill the bosses and run screw ins. might want to consider enlarging the spring seats too.

 

Considering the rest of your plans ,you won't see much benefit from changing to 2.02's. Just have the valve guide bosses
shortened to clear the cam lift and maybe give the heads a mild pocket port especially on the exhaust side. The low/mid lift flow of the vortecs is hard to beat out of the box. Porting will only be benifficial at much higher lifts then you have planed.
A new set of performance springs should be considered too.
Like Comp 981's.

 

ok,,,,manley valves and some cleaning up around the ports,,and intake side,,mostly,,,,,the springs will be changed anyway,,,and i think screw in studs will be on the cars ,,,as its cheap to do,,and piece of mind,,,thanks