I think built the engine is not a major issue for any shop can do it is same concept and after market performance parts is plug and play for RB26 but most important still depend how you tune it. FYI HV & TC car also tune at Viswork.
I should agree with you when came to engine build it require alot experience. Of course we won't give Tom, Dick and Harry to build the engine but I think for those well known garage should not have a problem with it.