I'm no expert in this area but my gut tells me it would be prohibitively expensive and you might not get the results you hoped for. Probably cheaper and get a better result by selling your gas MH and buying a diesel one of similar vintage.
Check out these guys. fordcummins.com - Increase Horsepower with Ford Cummins Diesel conversion kits. I know it says ford but these guys know there stuff. They have adapters and stand alone computers and knowledge. 12 valve cummins is the way to go but may be cost prohibitive. Could be upwards of 10,000 dollars depending on how much you can or are willing to do. Tons more low end torgue and pulling power over the gas motor and probably increase in fuel economy also.