You say big kid, strong hitter, biggish arm ....
Stop right there. Those attributes will get him lots of looks especially at D3 -- but also at higher levels.
You say weak defense -- okay he's not going to be a MIF or play CF. (Can he run?)
But a big sticks speak loudly especially when wielded by a big body.
Defense -- that can be improved with work. But sounds like he has that thing that college coaches love above all else - -- MAN STRENGTH -- especially when its accompanied by a swing that allows that strength to be delivered to a baseball in a punishing way.
They are willing to overlook a whole lot of flaws for that.