for an 80 lb kid, you'll need some new bushings.
his weight wont be able to compress those bushings at all, if they're anything like the bushings on most completes.
order some khiro white barrel bushings (2 sets), and put those in.
to you, it should feel something like trying to balance on a marble, for him, it should feel good.
if you dont mind spending the extra 5 or 10 bucks, buy 2x white, 2xorange, 2x blue.
with the blue, it'll feel pretty turny for you, and quite stable for him.
orange is between the two, but hard enough that i ride it on some boards, in the front truck, and i weigh about 160.
oh.. about the bushings, keep the back a little stiffer than the front, whether that means tightening it a little more or putting harder bushings in.
keeps things more stable that way.