383 6-71 build ?'s

I would look at a 8-71 instead of a 6-71. A 6-71 is on the small side for your cubic in displacement in my opinion. You will want around 8.5:1 so it wont be doggy & run a 112 -114 c/l cam . & make sure you get custom blower pistons. They have a lower top ring landing for heat . The manifold will cost you $900.00 from BDS . It is a expensive piece unless you want to fab up a low profile intake . I did a blown 383 years ago & it was a total Animal & you know how a well set up 383 revs to the moon in a naturally aspirated build. It was crazy with a blower. I used diamond racing for my pistons & got my crank & heavy duty rods from OHIO CRANKSHAFT. Check them out ! I have been very happy with all their stuff.
Whatever you decide to do ,just make sure you do the right cam . 110 -114 c/l . I like 112-114 the best & I do mine on a 114 ,but it will make extra heat . Make sure you have a very good cooling system & I use restrictors instead of a t-stat . I had too many problems with t-stats fluctuating & solved it when I went to restrictor style.

Good luck