how hard is moter swap

[bryguy00b]

going ot look at a 91 GMC sanonma tomrrow for a DD with a good body but runs bad...200 bucks he wants. says it miight have something to do with a lifter..ive never messed with engines that much..so is it something fixable or would a moter swap be a better idea..anything i should look for on these trucks..bont know much about em.

 

[Confedneck]

is it a 4.3? or i4? or what? either way putting a motor in if you're gonna use the same as stock isnt that hard in those...