Now we are getting to the good questions. Just like valve clearances, compression, tread depth, and almost every spec on any mechanical device, there are acceptable and unacceptable tolerances. From 10-4 in the 2008 FSM, the Axial Standard Runout is 0.5mm/0.02" or less. The Service Limit is 1.0mm/0.04". The Radial Standard Runout is 0.8mm/0.03" or less and the Service Limit is 1.0mm/0.04".
On my old GL1100, the Service Limit was 0.080", and the runout was 0.060", but it created a severe wobble, which necessitated the wheel replacement.
Since we are discussing fairly small tolerances, it would be best to buy/rent/borrow a dial/digital runout indicator and check both runouts with the forks held firmly at full lock. You could use a dial/digital caliper for a rough measurement, but it takes some bracing and a very steady hand to be even close to accurate w/o a runout indicator.
As I noted above, there are many possibilities for the wobble, including wheel and steering stem bearings. It would seem to me to be more logical to check/fix as many things as possible before chucking the cash at a wheel. Just from your story, my first suspect would be an unevenly mounted tire, but there are lots of things that can cause a 35-45mph front wobble. Including bent rims. I just prefer to check/fix the easy/cheap stuff first.
