Diesel Bombers - 94 cummins 12v good deal or not?

Hey i'm new to the site and could use some advice, i'm lookin at buyin a 12v auto(50k on tran) w/170k this weekend for 6500. i've looked at it already, but its got me a bit worried. Heres the details: bodies pretty clean for a dodge (very top of cab has a few primer spots, couple very small seface rust spots on bed and another small spot were 25cent sized peice of paint is chipped on door, other than that no dents i noticed and no paint or clear coat flake). It appears to need a new oil pan gasket (bad enough leak that blows oil back onto the tranny). Front right tire is cupping (worn pretty bad on outter, other tires are even wear but are low tread), drives pretty tight and straight down the road though. And the biggest worry i have is when i drove it i was goin about 35 and kinda got on it but not real bad and when i looked in the rear view there was a cloud of blue smoke covering the road (this is within the first mile of test drive), but i watched after that and never noticed it again even when really gettin on it. it rolled some coal if i really hammered down. then i noticed it had a quik puff of blue/white smoke (wouldnt notice unless you were lookin) when he started it to leave. the smoke issue only really concerned me cuz the truck should have been warmed up he drove at least 20 min to meet me and maybe more before (sounded like he had been running errands) and it only sat for only 15min before i took it for a drive. he said the truck is stock besides the brush guard/winch and air springs w/compressor and ext tow mirrors. Should i be worried about any of this or is this a good deal i should not hesitate on? :humm: