You can always get a "2nd opinion" as to what to do. You could simply replace the entire outside Heat Pump with an R-22 dry unit. You would then have a 13 SEER heat pump, mismatched to a 30 year old (probably 8 SEER) indoor condensing coil. Will it work?? Heck, who knows? What will the efficiency be? Again, heck who knows? Will you have a warranty? With that mis-match? Again, heck who knows? I'd imagine you'll have severe problems right away either in the heating or cooling cycle, possibly both due to freon charge difference. Would we do this for a customer??? Heck no, don't need those kind of problems! Kind of reminds me of the Johnny Cash song about building his Cadillac one piece at a time. Possibility of a huge, expensive, inefficient mess? Pretty darn high.