i think it is a 1986 not 1987. looks like a long leg transom and i believe they went to extra long in 1987. first two digits of serial number will tell.
i had a 1986 gw190 with a johnson 120 and it was a truly great boat. just loved it. mine would do 35 mph with a 15" prop at 6000 rpm and jump on plane. not a bad motor at all for that boat unless you need to exceed that speed.
but mine was also in a lot better condition than that one appears to be. there are so many unknowns there. condition of fuel tank and transom and stringers and waterlogging would be the top of the list.
if you are even thinking about it, i'd take it to a weigh scale and weigh it and then subtract the trailer weight. boat and motor should weight 2500 lbs dry. add fuel and whatever else.
i'd also pulls some transom screws and drill into the transom from the inside with a cordless drill and 1/8" drill bit to see what the drill tailings looked like.