I spent ten weeks in Tulsa (Jan 2002-Mar 2002) at what was Stapleford USA, (now Riverside Flight Centre), doing my FAA PPL and hours building before coming back to the UK to do the ATPL ground school and CPL etc etc...
They were absolutely first class through out. They're a small school which, at first was a bit perturbing, but what they offer is a very friendly, personal service. At the time they had 3 C152's. I think they may have another one now along with a C172 and Beech Duchess. All the aircraft were absolutely immaculate.
Go for it! I would recommend them to anyone.
The reason for their split with Stapleford in the UK was a "conflict of interests". Some politics going on there, which to be honest, I'm not all that interested in! What I can say is if you were to walk in to Staplford UK and tell them that you did your PPL and hours building in Tulsa, they would know that you'd been trained well. They took me from scratch and I came home with a first time pass in the FAA PPL skills test and 100% in the written exam! If I can do it, anyone can!
Hope that puts your mind at rest.