Daz,
If it was me, I would buy it from a supplier on the basis that i could return it (damage free) if I couldnt make it work, with undamaged packaging etc.

If u could make it work, any mods to make it work could be shared with the supplier, which may make it easier for him to onsell more to people like ya self who have a good idea for the RFM machine.

In my case, If i was to buy one for a RFM, and It didnt work, i would just move it sideways to one of my other data east/segas etc, or send it back with prior supplier permission.

the only other thing/idea i can come up with Daz, is i could get the identical shaker motor/board/wiring kit that Stern/mark/rtbb/marco sell etc out of my Godzilla and see if beaky can make it work on the RFM   ( I dont think there is a current bally/williams brand new shaker motor kit for sale anywhere ? I could be wrong, but if there is a bally one avail, maybe someone else could list it here on the post to help out ?)