Not sure what you're trying to accomplish. "Could" be done easily. Just adapters to hang a 600 from 1200/midget style motor plate... Resulting combination has higher weight & CG along with lower left weight bias than a 600, coupled with significantly less torque and HP than the 1200- So really take the worst of both formulas. There are a couple DLH upright 600 chassis out there. Think Rick Cully might have them.

In either class, an older car designed for the class will be far superior than a hybrid of the two.