sounds like a hell of a deal to me....just be prepared for some work swapin everything to ur car, that could add up $$ fast...

A lot of people are trying to get a lot more than that for high mileage 2.3T drivelines, so I would say it's probably worth getting for $700 if it really has been rebuilt recently. I paid $800 for a parts car just to get the 2.3T and T5, but still had to go get it, store the car, and pull everything myself. Some of the purchase price will be offset by selling parts but there will be a lot of hours tied up in it.

One caveat is exactly how the rebuild was done. Forged OEM replacement pistons specifically for the 2.3T have been obsolete for years. Unless it was rebuilt a long time ago or with old stock TRW/Speedpro slugs, then the only possibilities are flat-top forged pistons or worse, cast flat-tops for a non-turbo. I suppose aftermarket forged pistons could be in it, but it's not likely given the asking price.

You heard it run? Is it in a vehicle?

I've never had a fresh 2.3T  , but good runners often blow around 145psi regardless of mileage.

2.3Ts with the easier-to-get flat-top pistons will often ping at stock boost levels (14-15psi on "premium" mode, ~9-10psi on "regular). In factory 2.3T cars with the knock sensor still connected, they will nose over dramatically when pinging as the ECU pulls a truckload of timing to keep it together...and they may still audibly ping.