I'd never heard the SAAMI pressure of the max was higher then the 357 Mag. The 38 Sp yes, but the mag is a very high pressure round.
The other option might be to START with the 35 rem in Marlin and try the conversion in that direction. New barrel, lifter modifyed, maybe new magazine tube, but the 35 rem is pretty high pressure as well. It will handle the length no problem.