I’m starting to get optimistic that it just needs to be cleaned. Maybe at the most have the valve train redone
Funny thing about my 1997 F150 (4.2 v8, i think- been a few years)...
I bought it well used with about 125k miles. Sold it with over 250k.
At some point early in my ownership, i switched it to full synthetic oil and started having oil pressure problems. Switched back to the syn blend.
Ran a bottle of seafoam through it... started getting a little water in the oil. (You know you have water in the crankcase if you get some brownish/whitish foam building up on the dipstick) Apparently i had structural carbon build up the was sealing some holes. Never used seafoam again in that motor.
Find a youtube showing some one removing the valve covers- they're just stamped covers that go over the ends of the valves, bake springs, and rocker arms. Sometimes, they just snap down, no fasteners required.