BLUEMOMENT

Dave, could the lead not be removed first then replaced after galvenising?

Probably, but it's not a job I'd fancy doing. With all that metal to conduct the heat away you'd need a pretty big blowlamp.

OTOH, and thinking a bit more laterally, induction heating might work better. A couple of dozen turns of welding cable wrapped round the business end of the anchor and connected to a welding transformer might just do the trick...