It's a 1997 z with close to 250k
He said the smell of fuel is coming from the coolant resivor? Never herd of this before?
Also doesn't start but will sputter?

I'm trading a bunch of audio equipment for it that's just sitting.
What you guys think deal or no deal

If fuel is getting into the coolant that means most likely it has a bad head gasket and the fuel injectors are leaking into the cylinders and getting to the coolant from the head gasket. That would be the only way I see that fuel could get into the coolant.
I would look at the car real good. Look at the oil. Look at the coolant. If either looks milky (like chocolate milk) or looks sludgy, then that's head gasket. Leaky fuel injectors can be tricky too. That spells bad news and can catch fire if not repaired right.
To me it sounds like the car has some serious problems. Idk how much your stereo equipment is worth, but think about that.

Personally, I'd think about what i'm trading and what I'm getting. If it's worth it, and you need a parts car, then I'd do it. If it's worth more than $600 or so, I'd pass personally.

Also, being an LD9, and not running, you dont know if it has an oil problem too, a rod knock, or timing chain problem. Idk man, I'd probably pass.

There's a bunch of emissions-related components near the coolant reservoir, like charcoal cannister and purge valve. I'd start looking there.