Komatsu PC250 thoughts?

Guys - looking at upgrading excavators from a 1978 Cat 235 to a 1994 Komatsu PC250L-6 with a hydraulic thumb. Guy says the rails are shot, says bushings are cracked. How big of job is it to change? What is a rough cost of parts? We can do mechanical work, have a large shop and have done a lot of motor overhauls and such so that doesn't scare me. He says it works great other than that and is still working you just don't want to track very far with it or very much. We are really in need of a hydraulic thumb for some jobs and to put one on the old Cat is not very cost effective (no auxiliary hyds). The Komatsu has 17K hours on it though, (however our old CAT has 22K hours).... is that to much? We won't put a lot of hours on in a year. We've had some issues with the old Cat and hydraulics and leaks and are still trying to figure out what's going on with it but as old of machine as it is and as many hours as it has I don't know how smart it is to put a whole bunch of money into it. What would a functioning Cat 235 be worth? Boom and bucket are good shape, pins a little sloppy will dig a deep hole pretty quick, most of the hydraulic issues/leaks are tracks and swivel leaking.



Just looking for some opinions as I'm pretty new to big equipment.



Thanks.

Chris