hillbilly customz

Well I am new to this forumn but I have already learned more about my cherokee than I have ever thought possible. This site is awesome. The question I have is I just bought to cherokees really cheap from my inlaws. One was a wrecked 88' that ran good, and the other was an 87' that had a bad motor. I am in the process of building a new shop and I dont electricity or doors on my new shop and I didnt have room in my cabinet shop to do a motor swap so I let a friend of mine who owns a mech. shop do the motor swap since they were slow. The problem is when they went to start it the rockers where rattling so they pulled the valve cover off and only the two back rockers were oiling. Since they back two where oiling the pump should be alright. Right? Anyway I dont know much about these 6 cyl jeep motors but we are afraid to let it run very long. Could the lifters have become "unprimed". Anyway any suggestions would be great.