273 Radiator for 340?

Why not just get a factory style replacement like from classic industries? I have one on my demon and my car stayed at 180 and maybe crept up to 190 in stop and go in 95 degrees. Just recently replaced the 5 year old murray water pump due to some slight play in the bearing, with much advice from the members on here i upgraded to the milodon high flow water pump paired with a milodon high flow 180 t stat and it seems much more efficient. Actually can see when the t stat opens, opens at 180 and drops to 170