I don't think 300lbs is out of the question for Hulk, especially given the fact of his height plus at times he did not have top notch conditioning, but was just really thick.
They showed scenes of him working out on Hogan knows best; Bubba the Love Sponge worked out with him all the time a few years ago. He'll probably continue to lift until around the time he dies.
I definitely believe Hogan was 300+ lbs.
Because the guy was never in shredded condition.
He always looked to be around 15-20%, high teens or low 20's.
Never seen abs on Hulkster.
So just do the math on that.
If you got a bodybuilder in contest condition, that's around 5%. And the best comparison I can come up with is Ralf Möller from Germany. He is 6'6'' and competed around 275 lbs according to musclememory.
So add 15 % of bodyweight to that (lbs) and you got 316 lbs.
That may be oversimplifying it.
But my point is that it's reasonable that Hogan walked around at that weight, given his height.