Best 904 core?

I had a 77/904 built with lower 1st gear,change out the drum,red racing belts,9 blue clutches.I run the conv. U-joints 7260/7290.My cars 60fts are 1.56,1.57 behind the 410.Any good trans. shop should be able to build you what you want.I got advise from 346Duster(Chris Andrews Racing)he runs a trans shop and also races with a 904.Good Luck.