Will a f115 sink me?

I have a 17 ft aqua sport. I believe the actual model is an osprey. Original dry weight is around 1850 lbs. I'm not the original owner and it's had improvements/modifications done and refurbished before I bought it. It came with a 100 hp mariner, 1988 on it. I know... It actually ran great until just a few months ago. Blew the lower unit and ended up scrapping it. I have never been able to find the specs for the mariner so I'm not sure exactly what it weighed. But it was heavy, just not sure how heavy. I grew up with yamahas, so I decided to switch my controls and harness. That's all done. If I had it my way I would put a 90 2- stroke on it, but as I'm sure you know they are not easy to come by. So I'm set on a 4 stroke. 4 strokes I have found to be a lil tricky. The specs on a 90 are almost identical to a 115, weight wise. I'm guessing that's why I can find used 115s but no 90s? I live in the Virgin Islands, so that also makes it tricky. I've tried the Florida thing before, don't want to do that again. I have found a used 115 here for a decent price. Only question is, will it be too heavy? Of course the guy wanting to sell it to me thinks It'll be just fine, but I'm not so sure. Does anybody out the have any advice or tips? Thanks in advance

a four stroke is going to be heavier....for example a 4 stroke 60 hp mercury weighs approx the same as the 90 evinrude 2 stroke that i replaced...as far as hp is concerned you do not want to exceed the specs on the boat tag for both legal and safety reasons...

boats built prior to 2002 were rated for 2 strokes and the additional weight of a 4 stroke were not considered..
http://www.searay.com/page.aspx/pageid/162277/Contact-Support.aspx