This car was relisted on ebay recently:
http://cgi.ebay.com/ebaymotors/1973...rs_Trucks&hash=item23209d85b2#ht_30024wt_1182
I was actually at SF Sports Cars looking at something else (a 400i manual - not for me but I'm glad I went down there since I've been fascinated with that car for years and now I'm over it; and on a lark a 575M - the 550M with the manual could be for me) and took a look at this car. I looked under the hood and in the trunk as well as inside the cabin, but didn't crawl around underneath.
The mechanicals seem to be very well done. It's pretty clear that (unlike my approach) they hammered the fire wall back or something similar, which is a common way to do this conversion and leave more space for the fan in front. Brad claimed that the car had never had any rust - it looked to me like there may have been front rocker rust at some point, but even if I'm right it appeared to have been properly addressed. I would certainly expect a completely rust-free shell for this money, and I didn't see anything that would indicate otherwise. (If I was buying, I'd have looked underneath.) The only thing that did worry me was that I didn't see any significant chassis strengthening beyond the strut tower bar. If this were mine, I'd be worried about chassis flex (and in mine, I was and addressed it). It might be possible to fix any problems that arise with a trunk crossbar and other outside reinforcement, but it would be something a buyer should think carefully about.
I'd also want to bring the interior up to the standards of the mechanicals, but since that was the easiest part of my resto that doesn't bother me as much. Like others, I strongly suspect it needs racing seats or some sort of lateral support.
Bottom line: it would be tough do this conversion this well for the asking price, unless you do all the work yourself. If you're looking for an S38 car that is already driving to take the last restoration mile (rather than spend 18-24 months on your own project), this might be an option to consider.
FYI - Brad (the seller) was a really nice guy, willing to talk cars as long as I was willing to stand there, and I would be happy to do a deal with him. (Probably on a 550M or F430 spider assuming I can convince the wife.)