I had a 84 242 LS, the last year I had it I dropped a new 350 325 HP Michigan Motors engine in it. I got 40 mph at 5000 rpm. No way you will get 50 out of that boat, you just won't see it. You may get 46-48 with a 3 blade but you will not be able to get out of the hole. I finally sacrificed top end and went to a Rev 4 15 pitch, 40 mph no matter how much weight, every day any conditions, and my hole shot was awesome!