Tua will find that chin, Sharkey had nothing to keep him off, Tua will force him into a corner and find his chin.
I’ll say what I always say about Sharkey, he was a bipolar fighter and if he shows up in his “up” phase he could make it interesting because IMO he’s closer to elite status historically than Tua.
Tua was easy to outbox for long stretches. Guys like Oquendo and even Rahman who was no boxer outboxed Tua until he got clipped after the bell. Sharkey was a much better boxer and could theoretically outbox Tua, the question is, is Sharkey big enough to withstand a modern heavyweight with 40 pounds of muscle on him. My guess is probably not. But historically Sharkey rates much higher.