"Gem" or not, it's hard to put a positive spin on the situation. Your pride & joy suddenly became a fixer upper & even if you'd been dreaming of building an engine it would still set you aback.
I would do the "basics" mentioned earlier to preserve what's left & diagnose as much as possible without tear down. Based on those results, pulling the head for additional inspection would be the next step before a final decision. That assumes time & facilities to do the head gasket as you mentioned you expected you could do.
At that point you could make the next decision, whether it could go back together with head gasket & possible minor machine work or if it needed more inspection & possible repair that may be more than you could do.
I've been in the position (kinda), had a '53 Willys 4WD Wagon I'd fixed up a bit & paid for an engine rebuild on. Engine ate a bearing on a trip & needed new rod bearings installed where I was (Columbus OH). Poor rebuild, rod caps on wrong rods. Got a new crank/bearing set as the only warranty payoff.
At the time, I didn't have the time/facilities to do it myself. Ran fine, but I didn't know how long that would last (ran for years in light duty for the next owner, don't know when it needed engine work). Graduating College soon, I needed something dependable as I ended up living far from home in apts. (only 1.5 yrs, couldn't know then - near home later wouldn't have helped anyways)
Only sensible course was to sell it to a Collector who could maintain it as a fun vehicle, not a DD. Missed it, but I was in no position to keep a collector vehicle & other things were more important later when I could. (owner wasn't selling when I still saw it on occasion anyways, did check that once)
You could decide it's not worth diving into the head removal portion after initial maint. & checkover - depends on how that looks. I'm recommending the minimum just to preserve the most value if you decide to sell.
Don't have to decide today I assume, final decision will depend on your situation as much as the problems that can be confirmed or ruled out.
Keep in touch, folks will help out as much as possible.