Failing head gasket 2008 Tacoma 2.7L 199k miles

Just bought this car, got it checked out and it just needed regular maintenance on it for its mileage, which I had done, otherwise looked good. Put ~1,000 miles on it then the check engine light came on.
Cylinder 4 on my engine has been misfiring, didn’t catch it early enough, now I have a failing (cracked) head gasket, 428ppm coolant leaking into engine oil, and maybe a cracked cylinder head. I am trying to figure out what’s more worth it, getting a new engine or trying to get the parts replaced and installed. I just replaced the computer and a failing fuel injector before the engine continued to misfire and my mechanic discovered this issue. Any advice appreciated!