You might do well to check out Inverter Drive Supermarket as suggested.
I recently purchased a 3/4 H.P. Marelli three phase motor from them, it was frame size 71 with a 15mm dia. shaft. You should be able to get full dimensions from the Marelli website.
I was surprised how very much smaller it was than the old Brook Crompton single phase 3/4 H.P. motor.
Don’t forget that Inverter Supermarket also sell made up screened cables for connecting the motor to the inverter. It all went like a dream.
Len. P.