ROLYNN PRECHTL K7DFW
It isn't that they were selected, the 2N3055 devices at the time were all homotaxial and had low beta compared to more modern versions.
Even with this in play some HV circuits were cranky and wouldn't do well with very low and very high betas.
Look for a 150-0140-xx with a beta in the range of approx 20-50.
We fought this in the B Phase of the 611 and I'm familiar with the problem.
Tek Bvtn and Sunset 1966-1971