RD1 with 274k - Replace cylinder head or "rebuild"?

I have a 2000 CRV with an automatic transmission and AWD, I'm the 6th owner and have put ~60k miles on it and it's started showing its age. I did the valve lash adjustment about a week ago which was relatively painless and solved a misfire, but the car still runs rough at low rpm/idle and is continuing to show the infamous P1399 code.

I'm fairly certain it needs an exhaust valve replaced on Cylinder 4 but haven't been able to do a leak down test yet (will be doing that in the next few weeks, car is parked and won't be driven until then). I'm an idiot and drove the car more than I should have prior to doing the valve lash adjustment so bear with me as I'm still new to the deeper level of self-maintenance.

Prior to the valve lash job, I took my car to a local shop for everything, but they can't do any in-depth work to the motor (they're reliable and trustworthy, but made it clear they just don't have the tools or time to do work that requires removing the cylinder head).

All this exposition to ask, if these issues are only caused by a burnt valve, should I "rebuild" the current head and replace everything piece by piece, or should I order an aftermarket cylinder head? I'm hesitant to pull one from a junkyard or facebook marketplace because there's no telling if they're in better shape than my current one, but I'm still learning and open to guidance.

I know with enough TLC these B-series motors will run forever, but I'm also aware that "forever" usually means 300k miles. I can't afford a car payment, and don't want to give up on the old girl if I can help it. Its been a great car and I'd like to know if there's a clear best course of action.

P.S. If you can believe it, even after 6 owners and 274k miles, it still has the picnic table!