Not Running Smooth

Good morning gentlemen. I am new to this forum and all forums but I need some input. I have a 1983 bronco with the 4.9 4 speed. I bought it a few months ago from Washington state and it is very solid. I freshened up the interior and did brakes, exhaust, and some suspension work. I just installed a new 11” clutch and was planning on registering it this week. However now it is running VERY rough. I thought it was a fuel issue and went through the usual steps and it is no better. My mechanic (friend) looked it over and we put on a new cap, plugs,and wires. Still no good. We are thinking a bad lifter or something else in the valve train. The truck has 250,000 miles on it and seems to be pretty original. So here’s my question… do I take off that head and have it rebuilt and install new lifter’s and push rods. Or just buy a new head for about $900. Or do I get a whole new engine for about $2000? Or a 351 for $5000. And would that tranny/ clutch bolt up.