6.1 5 Speed Questions

I assume this build is sticking with torsion bars and a stock engine location (not shifted forward)?

For a budget build, it should be driver's side starter. A PS starter will require a custom starter mount and an aftermarket starter.

Only headers I am aware of for a stock location is TTI.

Any 5 speed that isn't the A855 will need tunnel work. When Keisler was around, they used to modify the TKO to kind of fit, but the driveshaft angles weren't the best. Keisler was bought by SST (I think?) but no idea if they still modify the transmissions. And if I was going 5 speed it would be TKX or nothing and pretty sure the TKX can't do the same mods.

Since they will have to build a trans tunnel and crossmember for the 5 speed anyways, I would suggest the Holley mounts/headers/TKX crossmember. Not a horrible cost, maybe $12-1500? But close to a bolt in deal minus some tunnel hacks. Assuming they have the V8 spool mount k-frame.