They're the same frame except the reeg mx rear top mount is slightly different to take the reeg swing arm and elka shock i'd go for a modified gp reeg frame with modified head tube angle..
since this thread is still here, I'll add a bit to it... How does the Sano cradle frame compare to the reeg and billetware setup? Is the reeg swingarm the only mono swinger for 70's on the market? what else is there?
If its a crf50 billetware frame your talken about the rake change isnt really needed, but if you talken about the crf70 billetware frame 3 degrees less is exactly what you want to do, thats what slowracer and I did handles unbelievable!!