I have solved the E8 conversion issues, so if you are interested, read on.
I struck out in finding motor replacements, so I began to think maybe I would luck out and find a set of MTH E8s that either had body damage or electronics damage that I could pick up on the cheap. (MTH bought the Weaver E8 tooling, so you can get a Weaver E8 shell on a MTH frame). Amazingly, the next day there was a set of PS2 E8s that had the PS2 electronics fried for a cheap enough price that I thought why not.
So I did an EOB upgrade and they are working perfectly with all 4 motors running off the same board. When I get more adventurous, I will put back the smoke units, drill the appropriate hole in the shell, and add the smoke stack (which is missing from the Weaver model). But for now, they will remain smokeless.
So back to the Weaver frames. I put the MTH shells on, but there are some issues. The front mounts for the screws are shorter, so I had to add some washers, and got them together. But they ran really bad, and made grumbling noises. I figured out that the huge motors were hitting the top of the shells and making all the racket, so more washers were needed to fixed it.
Looking over the frames, they were somewhat bent up in the middle so that also contributed to the motors hitting the shells. Now thinking back, I wonder if the bent frames was what sent me on this journey, and the reason that the cruise commander did not work very will in the 1st place.