i would be careful buying a rotten dog mpu.
A customer of mine has provided me with one to test with his sys11C boards i am restoring for him

there is a problem with the special solenoids section on the mpu driver board.

the problem is when you activate the top right  pop bumper it triggers the bottom sling shot, but when you activate the right sling shot it triggers the bottom sling shot also.

when you do a coil test all coils work as they should.

the fault is not in the wiring because it all works correctly with the WMS mpu / driver board in it.
 
Mind you this is a system 11c not 11A so you will get a different board.

If you can track down a good second hand mpu / driver board then that would be the best way to go.

I will keep you posted on the outcome of the sling shot / pop bumper problem.