As the story goes, the Prescott's with the lower rounded corners (or all of them) were copied from an old Mittenwald Klotz-scholl bass, so were the gear plates of the Allen bass as far as that loop at the top. To compare, look at the Allen beside 3 other old Mittenwalders posted here on the Forum;
Although not two plates on these basses are identical, they all have the rounded loop at the top.
So, mix a Prescott with a Klotz-school bass, refine it x10 (
) and there you have it,
'Americana' by JB Allen..