NADA says boat $1800 w/ trailer & motor.
But with that said I am sure it is with the original motor!!
The motor you have has a value of $5000 to $5700
So take the $1800 for hull & Trailer and take the low $5000 for motor as the hull price includes something for it.
You have $6800
Now take that and add or subtract for enclosures, Bimi top, Fiberglass repair, bottom paint & sanding, ect ect..
Make sure you go over the hull good, use a rubber mallet to hit the transom to see if there is any hollow sounds, Grab the motor while up and lift up and look for movement in the transom.
Floor ck for soft spots, it might be week over the gas tank cover cause this is were they all are! Not bad to fix, and some here have done it and guide you threw it.
Motor have a compression test done!!
Nothing will tell you better then a water test!! and if the guy isn't hiding anything he will do it in a min!!
Lots of V20's out there!! If this one doesn't work there will be others!!
So start with that $6800 and go from there,
if it needs near nothing then it might be worth more,
if it needs some then it might be worth less.
And if it just needs minor then it might be right on??
Is the trailer good shape bad shape, or have a trailer at all?
Good Luck! and welcome to the site!!