i have no clue as to the market, really.. me? that's a dinosauric carb app that I have less than a dozen of these days..

my life is all MPFI 6.2's, 496s and 6BT's, etc....
I've certainly never needed to replace one.. i do dozens of Jasper long blocks and occasionally swap an oldie like that over.. did one like that last yr, Crusader 454 in a mid 90's pig... that's strictly a bigger, inboard mill pan.. won't see that on an outdrive/sterndrive boat..
but I'm often surprised at other goofy, marine industries/markets around the country that i see.. meaning, freshwater lake stuff, in the midwest, etc.. it surprises me to see some of the stuff people are running.. have for sale, etc... when salty joysey has eaten most of that stuff for lunch 20+ yrs ago...
I would set the price toward the lower end of the others.. and you'll prolly sell it within 6 months or so.. someone doing their own older boat will come along needing/wanting one...