Do you know the car #? All SPF's are numbered either on the top of the upper frame front crossmember or on a tag attached to the passenger side foorbox (or both).
Superformance has made a lot of upgrades to their cars over the years. I think there's a thread here somewhere which lists what was changed at approximately which car number. I could be wrong, but I believe the change to knock-off type wheels was pretty early. A lot of SPF owners have made upgrades to their cars as they became available, if possible.
I would say $43K is a little optimistic for this one. Right now it's a buyer's market. This link will give you a good idea what prices people are asking for these cars.
http://www.cobracountry.com/cobrasforsale-cobras.html
But...hey, it can't hurt to take it for a drive and see what you think.
Good luck,
Lowell