I'd suggest offering the OM-PC in trade to a factory trained OM repairman like John Hermanson (www.zuiko.com), Clint at PhotoSphere (Dallas, dunno the URL), etc., for one of the pro-grade OMs like an OM-1, OM-2 series (OM-2, OM-2N, OM-2S), etc.
Virtually everything Olympus has at least some salvage value.
John and Clint are also well qualified to repair these cameras at the most reasonable possible rates. Check John's site for his current rate on that particular model.
The Zuiko 35-70 is a keeper; they all were/are.
Or shop KEH and buy an OM-2N. You can probably pick up one at their "bargain" grade for around $125 and they'll give you a generous inspection/return period. They might even accept the OM-PC as-is in trade, tho' you shouldn't expect much from them for it.
Just my dos pesos. I'm a confirmed OM fan.
Nothing wrong with the Yashicas. They'll accept the Contax SLR lenses, potentially a big plus.