As shown, the seat tube and head tube angles look very shallow and the there's not much BB drop. Consequently, I believer this is intended for a smaller diameter front wheel and matching fork. The lack of the proper fork would severely impact the value.

The vast majority of sloping tube TT frames that I've seen were intended for bullhorn handlebars. Consequently, the head tube is shortened and you do not you use an effective horizontal top tube for sizing. Most used an aero seat post, so they had a traditional amount of seat post showing and used traditional seat tube lengths for sizing.

Edit: The down and seat tubes are not aero along their entire length and appear round at the ends. This practice was pretty common in the early 1980s, when manufacturers wanted an aero frame but were still using lugs. However, it is atypical for what appears to be a TIG welded frame.