I don't know for sure, but with that small a motor I would guess at a NEMA-56 frame. That or a "C" flange if it was a custom job. A NEMA-56 base is fairly common for fractional horsepower motors. If you don't find the exact replacement, it should be fairly easy to cobble one up from any number of electric motor suppliers.
The six pole motor is a whole different ball of wax. My suggestion would be a four pole "farm duty" motor and juggle the pulley sizes to slow it down. A Baldor motor will be NEMA-56...... I have a few on my machines, they are TEFC, totally enclosed fan cooled, single phase, 120/240 volt, reversable. Of course, if you have 3 phase, well......
You might find one used that would work, but hang on to your wallet if you're looking for one at 1125 RPM new. With a 4 pole / 1745RPM motor, figure on about $200 bux. If you need to have it shipped, that's more. It's quite heavy......
WWGrainger is another option here, for both motor and mount.