Has the truck sat for a long time .sounds like a few stuck valves that caused the push rods to bend .take the side cover off and get some penitrating oil working on those lifter,and valve guids up top..It would not hurt to take the head off and have redone .you may be lucky with the short block just needing a good going through.I was given a 235 that i was told spun a bearing but only had a bent pushrod from a stuck valve but it also had some pitting in the cylinder walls from sitting .
