To know what you have there post some serial numbers, from the engine and drive.
As as side note, get rid of that edelbrock car air cleaner and replace it with a marine Flame arrestor. If the engine backfires the foam in the edelbrock can go up in flames, you dont want that to happen in your closed engine bay!
About 200hp...close guess anyway.
I used to have a 1987 1901 Medalist...it was a good boat.
Mine came original with a 4.3 and 2 barrel carb.
Good boat but they are not that heavy and do not like to run in chop without beating you to death.
Learn to use the trim in different conditions and you will get used to the ride.
I added Smart Tabs to that boat and it was a world of difference.
Mine had a foil on it when i bought it.I took it off and it actually handled better without it.
I then added the smart tabs and it would turn like it was on rails at full throttle...loved it!
If i remember correct i could get about 48 mph out of it.
It was a 19 footer so more weight than yours.
Pic of tabs installed,