There is a member on the UK forum called Peter Horton (Kent400)who is the go to guy for all the other members to get their clocks done by him. He charges very reasonable rates, $600 is an obscene amount to pay.
Peter did a set of CB550F2 clocks for me, fitted newly rezinced bottoms, the dishes were resprayed satin black and the needle damper reservoir was refilled. I can't remember what I was charged but it wasn't anywhere near $600, the clocks looked as good as new afterwards. Plenty of pictures of Peters work on the UK forum. As in
https://www.sohc.co.uk/index.php/topic,27365.msg254007.html#msg254007Found the cost, less than $100 for both gauges, that was a couple of years ago now but it should still be in the ballpark so to speak. I hope Peter doesn't mind me recommending him for work, I do know he's very busy at times though.
Also found some pics. Peter had to replace my dish on the tacho and the only one he could find had a very small dent in the edge near the glass, as I'm fitting chrome covers over these it wasn't a problem.