If you have access to a huge lathe that's capable of turning the entire wheel assemblies accurately, go ahead. Anything short of that will probably result in an unacceptable amount of runout due to inaccuracies in the cutting and welding process. Cut the entire center out of the RH5's all the way out where it joins the rim. Do the same with the replacement wheel, leaving enough of a flange at the outer diameter to get a good weld. Then temporarily tack the centers into place, and do a runout check before doing the final welds. Skip-weld the final passes so you don't concentrate heat and warp the setup.
After all this drama, there's about a 50% chance you won't develop stress cracks beside the weld beads due to heating/cooling issues. If you're a gambler, those odds might be acceptable. They don't give me the warm fuzzies, however!
Jerry
