I wouldn't pay $1500 for a stock 7M, unless it had solid gold valve covers. Hell, I don't think I'd pay anymore than the price of scrap for a 7M of any sort unless it was built by RCTS, Titan, IJ, or select few other members and companies well known here on SM. Honestly, I'd laugh at the guy and offer him $800, tops, mostly for the trans and wiring (assuming it's in good shape). For $1500 you could buy a whole car worth of original stock parts that will break! Sure, maybe it's rebuilt and it has 1500 bucks in parts in it... but how do you know what kind of work was done in it? You're better off with a freebie block and head and make your own mess instead of paying out the nose for someone else's disaster.
If you need the ECU and harnesses for the swap... there's tons of partouts all the time on here, that's alot less $$$ than buying that guy's overpriced crap.
You can buy BHG'd 7Ms for nickles or cases of beer, why pay money for something that is likely to blow up. Buy a blown 7M and build it yourself... that way, when it does BHG, you've no one to blame but yourself. Hell, I've seen people beg to have 7M's hauled out of their garages. I know a guy who proliferated a head of a half decent 7M block in an alley because the owner didn't care enough. Heck, I think that head is in my garage now.
Sad to say, but original and stock 7M's are more often than not scrap material in the making. It's wonderful to see an original 7M with high milage and a strong headgasket... but those are rare. So, if you want to stay 7M, find a free or dirt cheap BHG block and build that up with some stock components. And JDM 7M-GTE's are like a box of chocolates... well, chocolate milkshake, potentially... you don't know what you're gonna get. Most importers have some sort of clause that the engine has to be installed within 30 days by a licensed mechanic or they won't warranty anything. Their loophole against shade-tree mechanics (like me), I suppose. My JDM is surviving, probably on voodoo magic and hopes and dreams; I won't be surprised at all the day the headgasket finally goes.
Or save yourself the headache and go 2JZ-GE. Just remember that buying used parts is a guessing game until all the cards are on the table.