91 dodge shadow convertable, need help

91 dodge shadow, non turbo, automatic transmission, pk, front struts were shot, went over a few bumps on the highway and it put a hole in my oil pan. drove around 15 miles with no indication of trouble. Stopped and picked up my marshall cabinet and was on the way back, made it about two miles when I noticed my temperature was all the way over to hot, and oil light was on, took first offramp 1/4 mile away and stopped at gas station, checked oil, nothing added three quarts and it was still low so went back for a fourth and saw huge river of oil coming from under my car. towed it home. noise sounded like bad lifter but deeper engine noise.
got hole in oil pan welded up, replaced struts, replaced the rod bearings and the crankshaft bearings. Still sounded like lifters needed to be adjusted. find out lifters are hydraulic and self adjusting? I did take the hydraulics out one by one and soaked them in duralube, watched a thin stream of varnish creep out of each one. since they are self adjusting I cant adjust any lash out, and being overhead cam, there are no lifter rods. Friend of mine said put "seafoam" in with oil run it for a week and then change it out. ran it 10 miles, now oil can lights up on dash, do you think perhaps I may need a new oil pump or that the sensor or sending unit varnished up? how would i check to see which one it is?

what did the lifters look like? That being and overhead cam i would think that they had no oil that high up and and one or more became worn and now they are too short. IF im right about this i would change the lifters soon because once you wear through the case hardening they wear out very fast

i found the oil is not reaching the top end, figure either the screen is varnished up or the oil pump is shot. is it a lot of trouble to change the oil pump out and are they very expensive?