Cleaning engine rotors on the inside?
 

So I have a GSL-SE engine in my shed that's taking up space. It's there becasue when it blew an apex seal, someone decided to pull one of the rotors out and fill it with Plaster of Paris for some unknown reason. I want to save it and rebuild the motor into something cool. I don't know what yet, but I would hate to throw away rotors if they can be saved. The other rotor is fine.

I got it pretty cleaned up on the outside, but there's hollow cavity's inside the rotor that are still pretty gunked up. Is there an easy way to clean in there, or am I wasting my time.

I have access to a general repair shop that has very strong solvent tanks, an unlimited supply of engine degreaser, brake clean and other hard cleaning tools.

Any thoughts?

I don't know that a solvent, other than water, would have much effect on plaster. I use an ultrasonic cleaning tank and it takes carbon off the rotors, would probably take plaster off too.

tape all bearing surfaces good and gears and you should be able to bead blast or soda blast it all out without harming anything

I've got the outside cleaned up good, but would a bead blaster be able to get all the crevices and cavity's inside the rotor?