Unless you have access to a shop where they have fabrication, welding and machining facilities then you might struggle. Have you thought about the brakes and suspension being up to the task? The old set-up might not be good enough for the V8. Old straight 6 being cast iron, what's the V8?
You'll be looking at:
Engine mounts.
Gearbox mounts
Possible sump fabrication to clear cross members
Possible firewall fabrication to clear?
Possible tunnel fabrication to clear?
Propshaft machining and balancing
Radiator fabrication
Headers
Cables (throttle, clutch etc)
Gearshift linkage and tunnel positions
Electrical loom
Fuel supply
Not wanting to damp your enthusiasm, but you should take most of this into account when dropping in a different powerplant. You really need a good capacity engine crane so as to make a dummy run with the engine and gearbox to see what has to be made or fettled to suit.
I went through most of this when I shoe-horned a Rover V8 into my Chevette and Bedford CF van.