That's a shame, but always a gamble when they've been stood, old shitty mineral oil sludging up oil ways, things on the way out.
I'd do a comp test, see what's what, it ain't going anywhere now, whip head off and investigate.
All depends how ready you are to swop it out, required parts etc, compared to just getting it just back up and running.
If it's bust a ring, and ruined a bore, whilst it's doable in situ, you'll end up having a fight getting liner out , shit all over liner seat, faffing about getting liner shimmed etc
Putting a Cleon in it makes sense, but it'll take a fair bit of searching , ignition, bit of exhaust cut and shutting , etc etc
I've got an R4 complete engine you could harvest pistons, liners, head etc .....always very reasonable prices ....
Edit....what no oil???