I would look for compression somewhere in the 120s. Vary a few #s each but not much. I one dips down to low 90s I would pass. Don't take the sellers word for it. Easy to test while it sits in a driveway.
Be sure to run it, check for any nasty noises from the powerhead. Make sure it shifts properly, is pumping water, doesn't get too hot.
Lots of these V4s run a bit hotter on the Starboard bank, there is a mod to put a telltale up high on the Stbd side, this vents the "hi side" and helps. But still there should be no where on the block where you would burn your hand, if so it's way too hot. Uncomfortably warm is the limit on that. The exhaust manifold should run cool to lukewarm at idle.
If it's on a boat, run it. If not, at least run it on a stand and see if you can get it in a plastic barrel so there's some backpressure on the exhaust. Hard to tell how they're running when on a flusher, since even a sick motor might not sound that bad with no load on it.
Pop the lower gearcase drain plug & check for clean fluid, water in it or milky is probably the seals under the water pump.
Once warmed up, shut it off and hit the key again, it should fire off sharply without a lot of cranking. A motor in good tune will do this every time.
I'm a bit more extreme on compression readings, ideally they should be even across the board. I start to worry if they're more than 5 psi off but if 10psi or more I'd pass unless it's really cheap. Sometimes it's just carbon on the rings, but don't count on it!
All-in-all, that's a pretty good motor and if you find it's in decent shape, should give you good service.