IMHO, take away the badges and you might have a nice car, of questionable pedigree. Seller claims the body is Beck, but I didn't catch any claim about, or statement as to source for the chassis or the actual builder of the car.
Could the body be a Beck that somebody bought in a kit? If not, that would be a red flag as to the seller's actual knowledge or his/her veracity. I'd have a lot of questions before considering buying it and I'd have the PPI from hell performed on it.