Death_by_lysol

Helllo all
My friend has a 75 duster with a slant 6 in it
he has done the interior and exterior of the car nopw he wants a new heart. ( i know he did it backwards) Anyways i tried to convince him to drop a small block in it but he wants big block, so he are my questions:
Its only the major stuff im worried about right now, and it will be my first major implant on something thats older then i am.

Small block conversion
How much fab? engine mounts, direct bolt in? trans mount?
have to change sub/k/ frame at all?
is there another model the sub frame will work from?
Talk to a few ppl, they tell me a 340 360 will work, almost bolt it have to redrill the transmount hole 1 inch back, any truth to this?

Big Block Conversion
Have a 77 440 and 727 trans from some boat of a car, i cant remember the name of it....sorry.

Engine trans mounts ? Fab?
Change sub frame? if so what model? besides the obvious stuff, like shift linkage, fuel line, wiring, rad hoses, fan set up, driveshaft possible steering linkage issues, anything else thats gonna make me regret this conversion?

I guess i should ask these questions to....
Im new to this old stuff, so at the risk of sounding retarded, what model type is the duster?
Will this conversion work? either one?
anyone live in calgary alberta that can give me a hand? can pay, not sure how deep my buddies pockets go tho....

oh and one more thing, its a one off custom, and it looks amazing.....so if anything is do able please throw a brother a bone, this could be a big step in my life, and i dont want to skip it.

Thanks for your time.