I agree you done very well for 4k and yes Nyes is well known for great Service..I walked thru their shop about 4 years ago.
My engine guy said my 406ci could reach the 600hp mark with a Bigger camshaft and bumping up the compression to From 10:1 to 12:1.
Looks like your 383 has the same potential with little changes...thats a great thing.
have fun !
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Bjuice..
"I'M YOUR HUCKLEBERRY ! "