Dan:
If you were looking at an E Type the owner might have referred to it as an XKE. Three carburetors would mean that this was a Series I car which were produced from 1961 to 1967. The carburetors on the Series I cars were SU carburetors, not Webers. If, in fact they are Webers, you are not looking at an original car and I would be very wary. The owners comment that it is a "rare car" raises a flag; although the Series I is a very desirable car and not seen on the road every day it is not rare in the sense that a 427 Cobra or a Ferrari GTO is rare. Also calling the car "sort of a sports car" is an odd choice of words for the owner to use; the Series I is known by car enthusiasts as one of the purest sports cars and true "drivers' cars" ever produced. It doesn't sound as if this owner is very knowledgable about his car - not a good thing when it comes to E Types.
I don't mean to discourage you but do yourself a favor and become very knowledgeable about E Types, their quirks and what to look for when buying one. There are many books on the subject as well as plenty of info on the web. Owning a solid well cared for E Type is a rewarding experience, but owning a poorly maintaind one will be a hellish one.
Jeff