jeffreyhardy, The CM450 has a 16" rear rim, the 350 has 18" rim, but the outside diameter of the tire is the same, so you don't have a problem with fender clearance. Your only problem may be axle spacers, axle diameter and a different number of teeth on the rear sprocket .
Axle lists at:
http://www.clubchopper.com/forums/metric-chopper-talk/77043-jap-bikes-fork-tube-sizes-neck-bearings-axle-diameters.html
or
http://www.customfighters.com/forums/showthread.php?t=29199
or
http://hondachopper.yuku.com/topic/2755/JAP-bikes-Fork-Tube-Sizes#.T38CU9mKF1Q
A CM450 and CB360 both have a rear axle diameter of 20mm, but I don't see a listing for a 350.
The 450 may have 20 more horsepower than the 350, so watch for broken spokes! My CM450 has broken a few!
- Dwarf