I'll just machine up a shouldered shaft to go all the way through the spindle, with a thread on one end so I can fit a nut on the other end, to keep it secure.
As for the Norley..
Frame is chrome moly featherbed replica frame made in Aberystwyth, with tank and oil tank made by TAB2 in Wales, before they were called TAB2. It is the only such frame made to take the earlier XL1000 ironhead motor, rather than the later Evo engines. The Ironhead is less powerful and a bit heavier, but looks right to me, over the more modern Evo. Engine is lightly tuned, bike weighs 395lbs dry, 415 wet.
I know some owners have had TAB2 make them an alloy copy of the 961 tank, most are left polished in the photos I've seen. My tank was also left polished, but it soon got marked and scratched in use, so I had it painted after a year or so.