Hi,
This is Polhmann photo ref HD-19993, KRM with boots, alas not the definitive ones as we know them, filed November 24th 1952:
This is Polhmann photo ref HD-20116, filed July the 6th 1953, 54 KH airbrushed for catalogues, so there is an earlier proper photo, between 20093 and 20103, shots listed as "K Model with models", filed June the 15th 1953 (there are no other K shots between the KRM and the 54 KH shots listed) It shows boots AND old K geometry, so well before motor 2250:
To me, it's a no brainer, KH always had boots, never mind left over cowbells, they went in the stores as spares...
The question could be turned around and one could ask if late 53 K had indeed boots ; - )
Patrick