The fronts are fairly easy to change. Remove wheel & brake caliper. Undo hub nut & remove disc (rotor). Remove four bolts holding hub to rotor. Tap out the studs & replace with new.
That will sort of work but
and it is a big but,
the 7/16" studs have a completely different splined section to the 3/8" studs, hence why BL went to the bother
of making completely new hubs for the late Sprints (that came with the 7/16" studs).
You can hammer the 7/16" studs into a 3/8" hub and rely on a crude interference fit, if you wish, but please bear
in mind you destroy the splines in the hub doing so.
Yes, I know Rimmers' catalogue shows a kit consisting of 7/16" studs and 3/8 hubs. I have written to them on this very point
highlighting why this is wrong. They have not replied (it was over 15 years ago so I guess a reply is unlikely now).
When a stud starts spinning in a hub you'll know all about it
drilling them out is no joke.
Don't say I didn't warn you.......