Thirty year old tsio-360s?

[YankeeClipper]

Considering a turbo with 2500ishTT, but 400ish on the rebuilds, done back in the 80s and with no VARs. Has been flown a little in recent years, but not much. Even assuming good compression and other indicators, I feel like there is a substantial level of entropy and financial risk here. How much confidence would you have? What value would you put on such engines, or how would you factor the above into your purchase decision?