I think 'near' is a bit of a red herring.
Some options to consider include:
Dan Potter
@Dan@SJM ( Glastonbury I think)
Mike Woodford (Staines)
Paul at RSTuning (Leeds)
Scoff at EFI (Runcorn)
I'm sure there are plenty of other mappers worth their salt around the country, but these are the oft-mentioned names. Hopefully other members will be able to suggest alternatives.
Mike probably has most experience mapping with the RS2, not sure how much of a bearing that has on things. However, Mike no longer relies on RS owners for his income - he does it in any spare time he has from his new career.
My advice would be get in touch with Dan and/or Mike and talk through the options and your requirements etc.
Good luck, personally I think an RS2-style manifold would be a superb addition to your lovely BG!