Personally, I like the 400 block as it leaves more room in the engine compartment and for all the world a 500" low-deck looks like a 383; guess that's the old secretive downplayer gene in me. My last 2 BBMs were 440 blocks in early B bodies, and they were a pain to work on on the right side.
Another thing I like about the 400 block is the bigger cylinders help unshroud the valves/flow a bit.
Your situation may well differ, and it's just my opinion. Next BB I want to build would look like a stock 383 Road Runner but lays down 11s through mufflers...
My 505 has been painted up to look like a stock motor. With the Stealth head it fools a lot of people. I tell them it's an RV 440 with a cam and headers that I gave a nice paintjob.
Mine ran easy 11's at the track first time out on pump gas, through the mufflers, 3.55 gears and on street tires. I drive it everywhere.
I'd love to do up an early B body 4 door with a low deck block and make it all dirty and crusty looking under the hood. Tell everyone it's a 361. Dirt and rust blowing out behind it as you trip the beams with a high 10...
