Tread carefully here ?
I don't know about the G2 Bullets, but earlier Enfields had those nuts turned down a shade at one end,
so as to go into the CIRCULAR recess in the timing cover. This means hex nuts won't go.
But they may have changed this arrangement for the Bullets ?
Hitchcocks in the UK would have the real deal.
https://www.hitchcocksmotorcycles.com/partsbook-pages/1444I think 30 and 31 are what is required (no quantities listed, so cannot be sure.)
They look like just plain cycle thread 1/4" nuts.
Luke at Britcycle.com.au had them NOS at $1 each, cad ? plated.
You'd have to chase the washers - stainless ?
Interesting sounding project. ?
Can we see it when done