worn out 150's

well the 150's are the original 78's that came on the boat one will run and idle the other will run and idles when cold both motors have seen at least one over haul but the both have low compression on all cyl's 80 lbs + - 2lbs per cyl. The first thing I did when I got the boat was carbs and water pumps, but I have come up with another solution to my problem I have picked up a 1985 150hp that runs real well and is clean with great compression so I will take this motor replace the weaker of my pair and still be able to fish and i'll take the weak one and rebuild it. I sould be able to juggle the three motors at least long enough to save up to close the transom buy the aluminum to build my bracket and for shur by then a clean pair of outboards will come through the salvage yard.