Unfortunately I have seen a person bowl Two Handed in 1969, before Belmo was Born. Lindsay Sheehan used to bowl that way in practise, this was in the days when covering a lot of boards was not beneficial to scoring.
Lindsay was the only bowler I have ever seen, not bowl for years and could make a return in a Daybreaker, than proceed to average over 200 with a Conventional Drilled Ball. This was in the early 70's, even the Great Joe Velo in the early 70's only averaged 204 to win the SPC in the same Centre at Enfield ( this was the place to bowl Daybreakers, run by the late Bing Dallas). I think Lindsay also was runner up to Batson in the Australian Junior Masters when they were both Juniors, I'm sure Batson was a couple of years older as well.
He recently worked at Enfield again in the early 2000's, he gave bowling away in the early 80's, what a waste! He never bowled in anything more than Daybreakers as an Adult.
willey