Ok, here 's when we start the discussion between what you do, what you supposed to do and what you should not do.
The boat has a weight carrying capacity.
Let 's say you got a 12 fter, with a carrying capacity of 440 pounds, you weight 330 and your pal weights 250
330 + 250 = 580 .........uh, that 's 140 pounds more than the max carrying capacity of the boat. :-/ and you haven 't even included the outboard weight, let alone seats, cooler, batteries , seats and tackle.
The boat can carry you both ? well it ain 't gonna sink if that 's what you are asking me. So you can put 580 lbs of people in the boat, you are not supposed to do it but seriously you should not do it.
The boat can carry that weight but it 's unsafe to overload it.
So it doesn 't matter what you do, it matters what you should do and that is what counts ......... it 's your hide and the other guy 's hide what 's at play and your hide is an invaluable asset.
Safety comes first, never overload a vessel.
For you two big guys the bare minimum is a 14 ft with a 64" width ( 1100 lbs of carrying capacity ).