Thanks both for the above.

The receiving hole on the wheel carrier has a lot of material around it (so can be drilled slightly wider without any worries) - but is probably only an inch (or less) thick - and the bolt comes through the back of it slightly - but not enough, and with no room for a captive nut.

I'll have a look at alumaloy - but the threads need to take 100nm of torque - so not sure if strong enough?

And yep - the insert was a timesert - my friend used it for a stripped spark plug on a 1964 pagoda sl - said it was very nerve wracking, but had no problems - but again quite low torque on spark plugs.

Assume if I remove the carrier I don't need a new wheel bearing at the same time (drive shaft just presses out and slides back in) so just a new hub nut? Was a mission undoing all the old rusted parts and replacing all bushes and the balljoint - so at least dissasembly shlukd be easy - but I was so close to finishing the job!

Thanks again for responses.