I have an 89 Lx stock bottom end 302. It has an e cam, Bbk equal length shorty headers, 2.5" off-road h pipe and full exhaust. Holley systemax upper intake system, Anderson 4" power pipe, 24# injectors, Bbk high flow fuel rails, msd ignition, smog pump delete. About how much gain would I see out of these heads. I've read some forums that say the Pistons would need fly cut? Is this true or will these heads bolt up and go?
These heads would work fine with the stock block. You will need to check the piston clearance because these heads have larger valves. the rule of thumb is anything over .500 lift requires checking the piston clearance. These heads should give you great HP over stock depending on the choice of cam,