We really tend to go in the other direction here, returning "electrified" machines to treadle.
I would suggest you give it a fair try before you convert it. Literally millions of people have done it, you can too!!
With my "rant" over here it the general sequence:
First, determine if machine has motor/handcrank boss on the right side under the big wheel. (most made after WWI do have this). It is a rectangular raised area with a threaded hole in it.
If YES, then all you have to do is buy a motor, mounting bracket, and cord set with foot pedal.
If no, then you have a LOT more work involved, drilling and such.