I think it's too bad you fried one of the radios, as using both of them would
have given you either AM Stereo or the very desireable rear-seat entertainment
system.

If you're stepping back a little to 6-volt, why not go whole-hog for the
headlights and convert to acetylene lamps?  Easily found in any junkyard that
has a few Stutzes or Hupmobiles in the back.  Since you have a Westie, you could
plumb them into the propane tank and then not have to worry about carrying
calcium carbonate to make acetylene.

Attach the valve to the stalk on the column so you can boost the propane and get
a high-beam effect.

As for the starter, junk it.  The same junkyard that has brass-era headlights
should also have a few hand-cranks lying around; open a hole in the rear bumper
and crank the thing - didn't the early loaves have an opening for a crank?
Alternately, said yard probably will have some wrecked Stuka divebombers, which
IIRC had a hand-cranked spring starter that surely can be fitted with a small
amount of bracketry.

I will leave the Me-109 engine swap for a later missive.

Yr Hmbl & Obdnt Srvnt -

ed devinney