I just had Tachman reface and recalibrate all of the gauges on my 67 instrument cluster (with tach and clock). I had him do the 3 wire tach and quartz clock upgrades too. The turnaround was pretty quick (maybe 2 weeks), the communication was good and the work (aesthetically) looks great. I just can't comment yet on how everything works as my fastback is in the paint shop right now. I have attached a picture of the entire cluster, complete with a new Burton Antiques bezel. I can't wait to get this installed!
Most instrument repairers or those in the avionics industry should be able to do TACHS incl old Suns etc - some old radio technicians can be pretty good too, as there's both mechanical movement & electronics involved too.
(I've rewired/modified some to work with different eng cyl #'s for eng swaps...)