2.5 years is not too terribly long for the engines to have sit. I've
known of several aircraft in my area that have sat unflown / unrun for
much longer than that, without having the engines prepped for long
storage beforehand, whose engines were still in remarkable condition
after the usual basic maintenance tasks were done to revive them
(hoses, batteries, filters, AD's complied, etc.)

I'd be more concerned with looking for nests and other damage by
rodents, insects, birds, etc., since I once saw a plane that sat in a
hangar unflown for a couple years whose ailerons' movement were
severely restricted due to mud dauber (mud wasps) nests build inside
the wings on the control bellcranks. There were also rodent nests and
chewed wires in the aircraft.

Being a retract twin, I'd also have it put up on jackstands and make
sure all the landing gear mechanicals and electricals are in perfect
condition. I'd want to see the gear flawlessly perform a couple dozen
cycles while the aircraft sits on the jacks just to make my wallet
feel better before flying the plane.