HB .61 engines were once called the "German Veco"

The early .61 engines had a different size front bearing and were very hard to find replacements. You can still find bearings for the later models and I don't remember any way to describe the difference.

Later on HB also made your PDP (Perry Directional Porting) version and later on a pretty hot version with a black head called the "Blitz."

They were very rugged and powerful engines.