My doomed 408 build

One thing that comes to mind is that a Blueprint 408 crate engine with their warranty is looking pretty sweet about now. Yes it is, hindsight is always 20/20
Your builder sounds like a real dick to me. Sounds like he's at a loss here
He should make it right, lord knows how much you spent there on this build. Agreed
If it's a parts defective problem, he could back charge the supplier in yours and his behalf. Mfg's will tell the builder to go pound sand as in " We've never heard of that issue before!?--must be you--click...dial tone. The only recourse for the builder is to boycott either that product or the offending company's entire line.
To me, the only reason that he wouldn't stand by his product/build is if he screwed up.
That's the thing that truly sucks about some people.
Good luck, i hope it turns out well for you in the long run............
J.Rob