350 to V6 Swap Tranmission Location

[1972RedNeck]

Have been collecting parts for my 350 to large V6 swap (stroked 478M) in my '72 K20. Have a complete 305 out of a '67 K2500 with bellhousing, cross member, etc.

The question I have is a minor one.

Is the transmission mounting location in a 4X4 the same for a small block Chevy and a GMC V6? I.E., when I bolt my V6 to my SM465 and NP205, will I have to slide the whole nine yards forward to gain firewall clearance to make it fit? Will the GMC bellhousing even bolt to the SM465? (I assume it had an SM420 bolted to it, but it very well could have been a NP435 as well)