I think both guys would walk into something from each other and then be wary. Tua outworks George in a boring fight.
Tua would be intimidated by George from the jump. And once George tags him, he'd go into a shell and be outboxed. Foreman by UD. 70's Foreman stops Tua in 6.
What did George say himself? 'If I can't beat David Tua I can't flip a hamburger'? Foreman circa 94 would keep keep Tua circa 00 on the end of his jab and whack him with the uppercut enough early to keep Tua honest (read lacid) for the rest of the fight.....:: UD Foreman. Prime Foreman probably stops him in 4.