Ulf,
As HL said any SBC will bolt right in. I have a 350 in my 1956 Tow Truck and it runs great. You will need the V8 motor mounts sold by all of the vendors (same as the pickup trucks). The clutch linkage will work, it might need to be adjusted a little and you'll need the V8 throttle linkage. The radiator will need to be moved back about 5" or you'll need a deep fan shroud. You also need to change the ignition switch to one that has the "start" position as you will loose the foot start when you convert. The rest is just normal re-working the electric, exhaust, vacuum and fuel lines.
You will be happy with a 350...lots of power and faster speed.
The Bell Housing will need the dust shield (two pieces, bottom and front).
Mike B
