Need info for the purchase of a motor for an old craftsman scroll saw

I have an old Montgomery Ward scroll saw probably about the same age as your saw. My father-in-law gave it to me . He had put a 1/6 hp 1725rpm motor on it with 2 1/2 in pulleys. At 1725 SPM I could not keep a blade in it.
After messing with the blade holders and other thing. it finally hit me that it might just be to fast. I now have a 2 1/2” pulley on the motor and a 6” pulley on the saw that give me about 700spm. It holds a blade well and saws 1/4 in plywood very well.
To figure speed divide your drive pulley diameter by the driven pulley diameter and multiply that times the motor speed. On mine 2.5 divided by 6 = .416666 times 1725 = 718 SPM
A link belt might give you less vibration but a v belt would probably be quite a bit cheaper.

-- Bruce