That's what the XR750 is,not just a dedicated flat tracker but for decades it has been the bike to beat,Harley has flat out ruled that domain.
Before the dual carbed alloy XR750 there was the Iron XR 750 and the Flathead KR750,all were H-D purpose built race bikes.
Thanks Y2K. Now that's surely one to have in the collection. I don't think Harley exported too many of these, they're quite rare in Australia.