I've dealt with afew motorcycle valuations over the years in the trade, definitely take it to a place the deals with resto jobs so they know the work and expense that goes into it, I'd imagine most main dealers would just throw an average book price at you. I'd also phone ahead and ask them nicely, agreed valuations take time from their day with absolutely no pay off. Some will do it via email with pics etc so it might be worth trying that before you travel.