I've seen the "small base circle" issue before. I agree, they look a little "short' in the bore. The oil "band" is also too low in the bore. Our solution to that problem is using the Comp 859 lifter (Pontiac) with the BBC link bars. The body is a little taller (about .080"), but the oil band is in the proper place for the "new" position. One 427 took 30-40 seconds to get oil "to the top" with the Crowers made to Chevy specs. After changing to the Pontiac-type, it took less than 5 seconds. That engine now has several thousand street miles on it without issue.
It's okay with me, what ever brand one is comfortable with. I just offer real-world experience to the situation. Crower and Isky definitely make good lifters. So does Comp.