I read some comments about this particular machine and the one that stood out was from Bob Kovar, years ago. He pointed out that the flywheel pulley is quite narrow compared to a model 111 and was made that way for higher speeds when sewing long seat covers, banners and the like. Unless you have driven a clutch car recently, you may not be able to feather it to a controllable speed. It will sew flat out at 2000 rpm or more, depending on the size of the motor pulley. Changes will need to be made.
Slowing down old beasts involves changing to a modern servo motor and probably adding a 2:1 or 3:1 speed reducer (plus 2 new v-belts). These will cost you at least $300.