You could consider Brian Taylor who is in Shropshire, he will unfortunately though have a similar work load to Rod Briggs, there is no reason why you cannot employ a competent engine builder local to you, there is nothing magic about the Weller Engine, it just takes care & attention to certain elements of the re-build.
There is good information available to you on the various web sites & the Forum & if you need specific advice that can be supplied, the traditional issues of liner sealing have been dealt with also if you have a UMB type engine then the line boring of the main bearing journals must be set up to maintain the pitch centres for the crankshaft to cross shaft to ensure you maintain the correct meshing of the gears!
Robin