Installed umi th400 relocation crossmember when I did my th400 swap on my 99 z28. Noticed my exhaust is rubbing factory I guess would call drive shaft loop. Where the y meets. Kind of thinking motor and transmission is rotated down towards the rear. Anyone else had this problem.

 

I can't help you with your conversion, but I had a similar issue with my 80e in my nova.
I used a gforce xmember and it does the same thing.
I had to buy a taller urethane mount and a 1/4" shim to get my distributor off the firewall.
Now it's "close" to where the th 350 was.
I would have been better off cutting and re welding the 350 crossmember the the $280 gforce.