Please help me figure this stuff out

Can you deck the block .015? If the finish isn't good enough, cometic/MLS gaskets are not recommended, so this might be something you need anyways.

I would recommend the 452's, they're pretty easy to port. With a Serdi valve job for 2.14/1,81 SS valves and my first porting efforts, 69.7/.100, 141.6/.200,197.7/.300,231.2/.400,240.9/.500, 244.5/.550 where they stall, but no reversion. That was my amateur first effort, my next set went 265/.550. That's with almost exclusively bowl and short turn work and a good valve job, and not anywhere near a "max effort" because it's for an endurance application and I don't want to go too thin anywhere nor increase runner volume significantly. S/F....Ken M