What I might look for is all the parts necessary to put it back together. Make sure he has them all, flywheel, motor mount brackets, pump drive, make a list before you go. That's if he has put a good low price on it.
Get the info off the motor or try and have it identified. Tractor wreckers can almost always i.d. an engine with a few pictures and they will tell you what you have. Seems to me now that it was a David Brown engine, not a Perkins. Some of the David Brown tractor engines were weak, with only 3 main bearings, the red DB 990's and the brown/ white 990's had those engines, and crankshafts are rare. There was a thread here somewhere showing several pictures of 580G.
I would disregard the hour reading, the mechanical tach drive cable snapped over time and some CK's, B's, C's, D's, and early E's can have very nice hour readings because of it.
Could have a lot of problems mating the 188 engine to the torque tube, but you never know.
To ramble on, I was told by an old Case mechanic that the farm tractor blocks from the 430 and 530 tractors had thinner castings and are not as desirable for a backhoe. The 188 diesel used a smaller liner flange before a certain engine serial# and I don't think these liners maintain their height as well as the blocks age. Some redo the block for the larger flange, as the 'small' liners and the correct 'fire ring' type head gaskets are no longer available. Phil