1997 F150 4.6 Low Compression #4 Cylinder

1997 F150 4.6 125K miles, misfire code, shop said #4 cylinder only 60 psi on compression test, all other cylinders fine.

Mechanic said likely valves or head gasket, and that code isn’t coming up on the road but only at idle, suggests cylinder is firing at higher rpms (?), recommends just drive the truck until it drops. Truck starts, drives fine, slight idle roughness, feels/sounds smooth on the road. Mpg crappy but it only needs to go to lumberyard and back.

Thoughts - on how to get a better diagnosis and/or what action to take if anything?

This is a cheap beater truck I bought for a 9 month project, planned to sell it after. Tho I think it’s kinda worthless as-is, potentially worth something if this were addressed. Clean straight truck, low-ish miles, decent paint, etc.

I have a shop, lift, tools, etc - just haven’t had time or really interest to work on cars in past decade (have switched to home improvement projects). I can do work up to/including pulling the head or engine - just would like to minimize time put into a truck that, so far, I don’t think of as a “keeper”.

What would you do?