Hi mates,
as to the peel engines. The correct numbers are 80316....., or 80416...
For the british market the Zweirad Union delivered about 120 engines, witch were signed with a "4" on the 6th rank. For example 803164788.
The 4 was never used for products within Germany. It seems it was a special code for Peel engineering.
Of course u could use different engines, but some bits needs to be changed.
Right mates, keep the Peels running!!!