I usually make my own rather than buying someones and only using a small fraction of it.....no one likes paying twice. I will source a spool poly mount insert and laser cut the rest. The trick/challenge for me is placing the HEMI in the optimum position (with my K, of course) and be able to add ECONOMICAL off the shelf components for ANY trans application with minimal mods to the body as far as the HEMI goes.
I am basing my application on a 4-speed or A/body 727 with no sheetmetal mods. the tunnel area /trans might have to be modified if a large OD trans is used....but that will be up to each builder, no change in Hemi placement will change that fact.
3/8" forward should not affect drive-shaft length issue unless you are way out there now. When I built mine I was told by the Dennys Driveshaft to have 1'-1.5" of area to move inward to eliminate binding....that is alot.
