Rob,
The bell housing will work. If the 318 is an A and is earlier than
'61, there may be a difference in locator pins? That A745 3spd will
work on either the A or LA318 provided the crank is drilled for the
correct pilot shaft bushing. Go to www.hrclutch.com and get a new
pressure plate, disc, throw out bearing and pilot bushing for the
swap. If you try for clutch parts elsewhere, make sure they're
getting you a 10 spline disc and corresponding parts. There is a
difference between the hydraulic and mechanical clutch assemblies.
The slant Six flywheel will not bolt onto the 318. If I remember,
you can drill out one of the holes and it'll work? If it were me,
I'd find a hydraulic clutch 318 [A or LA] flywheel. The mechanical
clutch flywheels won't work.
John