Hot 660. Rebuild or replace?

Hey all. I just bought an 05 660 Rhino, Thought it just needed a headgasket,(seems common) but turns out the engine has been hot.

Seems like the kid I bought it from only owned it for a few weeks and didn't know the guy before him wired the Fan to a switch and bypassed the thermostat. Spat a bunch of coolant out when I pulled the sparkplug..

Saying all that, what should I be looking out for? I planned on a new top end anyway, but what else? Is it likely the heads warped? Should I just look for another engine?

Thanks all.