There's lots more info in the paintball talk thread, it's all spread out so you will have to go thru it from the start.
https://www.automags.org/forums/showt...Rex-%28OLTR%29
As far as the Chimera, at a glance it looks doubtful but I don't know for sure. I would need a CAD or a frame to measure. See post #3 in this thread.