383 vs 400

i thought stock 383's were all low compression but advertised at 10:1 so you could blue print
them to the factory rating and be NHRA legal.I have never heard of stock 383 pistons sitting
above the deck but maybe some were?
..as suggested a 340 has some advantages over a big block in an A body.

Some used closed chamber heads. The 343 HP dual carb 383 was a holy terror in stock eliminator in about 63.