Might be a pain to check lash. You could mount the packs on that huge motor plate and maybe profile the plate to the coils? I have those headers on a low deck A-body and they are no fun. Makes things ultra difficult to work on. The starter was the least of it. Save yourself some time and keep the engine and trans. bolted up before you install in the car then let the heartache begin. I couldn't drop the motor in from the top with the headers on it on mine. I think I left the drivers side loose and married the pass. side as it went in. Your cut out core support may allow you to get lucky there.