The seats look like a Kirkey Racing Seats design. I think Kirkey has only been in business for around 25 years so it’s possible that car may have raced in a nostalgia series of some kind fairly recently at least by HAMB standards. Also has provision for drivers side window netting which would indicate it’s fairly recent. I sure some of the oval guys here might know.
Tri 5 frames were popular here in the North East for pavement cars .Running in the "Nostalgia Classes or Clubs window nets are required and more modern Safety Equipment like the Seat,Harness Net and fuel cells are overlooked meaning while not required for some stuff they are encouraged this car would be right at home mid 60s here .