New to forum! '84 with Big Problems?

Hi, I am new to forums so bare with me. I think I just bought big problems! I just got back to riding last summer and just purchased a ' 84 aspencade with 44k. I road an '82 the night before that was in ruff shape so when I saw this '84 in such better shape for the same money, I jumped on it. The engine was noisy but I thought that was just lifters and nornal engine noisy. The owner (2nd) said it had always sounded that way. I took it to a dealer and the machanic said he has worked on alot of these and never heard one sound like this. Sound does not change when clutching. He seems to think it's coming from the back of the eng. It also has oil on the left front rotor from leaky fork seal and throttle won't adjust down, no play, and turning the idle screw all the out doesn't do a thing. I paid $2700. Anybody ever have this problem. Dan