79 Penn Yan Repower Project

Hey everyone, looked and looked but cant seem find the answer I’m looking for, so here I am. I own a 1979 Penn Yan 30ft Sportfish that I am just about to start taking apart for repower. I have a few questions about whether what I had in mind will work or not. The boat currently has twin 120 hp Naturally aspirated 5.9 cummins engines paired with twin disc MG-502 gears 1.54:1 ratio. The boat is for sure under powered and most likely under propped with 16×15 4 blade props. The dilemma I am having is the 210 hp cummins engines I have to replace the 120s with have and even lower rpm rating than the naturals and the boat will not get up on step even wide open with current drive and prop configuration. The full prop diameter for this boat is 17 inches as it is a tunnel drive. My question is, what kind of performance should I expect? Id hate to dump a ton of money into the boat only to be stuck at 11 knots everywhere I go HA. Will 210 hp cummins turn taller gears say 1.2 or 1:1? Dont have enough experience to know. I had originally planned on rebuilding my twin discs but starting to think I need to shop for drives that will spin 17in props faster or higher rpm engines Let me know what Y’all think

Thanks JON