Alot of folks in the area use Mesa Machine in Escondido. Might want to check with them as an option.
I also have the number of a good guy who knows slant 6s inside and out.
My guess is that you are staying Slant Six...I am sure your first stop in that case would be Clifford Performance. That is what I was able to dissect from your post.
http://www.cliffordperformance.net/
Your build is limited only by your budget.
