I've emailed both and they both seem to be quite responsive.

With Bob Jackson, I also traded emailed with the factory manager. This summer the wait was about 10 weeks. I suspect it's shortened now.

Mercian is quite accomodating as Ken mentioned and I received a reply from them this morning (I sent an email last night). 3 months turnaround time, fully custom. Chroming on the rear is 50 pounds, front, 38 pounds. 4 months turnaround with chrome.