In some areas, there are no Limitations. I know I never had any problem buying a boat, or having the Dealer repower it with Engines that were often close to 50% higher than the Rating. I also never had any Issues with Insurance Underwriters, and I told them, in Writing, it had more engine than the Rating.You can put anything you want to, as long as it is not more HP than the boat is rated for .
When i checked last summer it seemed pretty good for the age no cracks no soft spots. I already took off the force 85 and double checked because last summer i tried tinkering with a 1973. Crysler 70 that i never managed to get to start it the magnaignition was fried.how is the transom on that 36 year old bayliner?
Around 1987 was when makers went to the standard OMC pattern so that may be a little iffy. No big problem, just a little more work if they are not the same.I have swapped brands of motors onto my boats. The boats never complained.
Seriously though, the Johnnyrude should have the standard bolt pattern. Hopefully the Force had it as well, so you do not need to drill and fill.