Not sure of the weight, but several have went to the inline 4 cyl Yam 200's. That would likely be comparable with your existing 200 2-stroke, and you would only lose some low end torque when planing or hauling your fishing buddies around.
Remember, if the scuppers are partially submerged, it makes no difference in the cockpit draining. I had a 232 Gulfstream with F200's and the scuppers were 1/2 to 3/4 submerged for the 10 years I owned the boat. Didn't matter.
One more thought regarding scuppers; On a 1992 boat, I would certainly have the hoses & connectors checked thoroughly if you do hang some extra weight back there. If there are cracks or other sources for water intrusion, having the scuppers even partially submerged would be problematical.