It just seems that the torsion bars a) wear out faster (I have never replaced a valve spring on any motor in my life) and b) they are not making new ones. As a racer, you would then be the worst case scenario for valve float with such a setup. You never had to do anything to manage it? Never replaced a torsion bar valve spring?The torsion bar valve springs are not a problem... all springs are torsion bars, don't see the problem... the problem with that head is there is no more cam followers and they have proprietary sized crank bearings, which are no longer available.
I raced that motor for more than 20 years. I still have a couple. VERY popular racer. Racers have been over revving that motor for decades.
No need to be afraid of that motor.