The valve lifter you want is 330-31, which can be easily modifies from a 330-38 readily available from Drags, except they are currently out of the bush. If i remember rightly the bush requires shortening a tad.
I think the Magdyno gear cover shown is the style that was used from 1936 although I believe it will fit.
Worldwide Membership Secretary
Semi-retired partner in Draganfly Motor Cycles