Just sharing a project done over the winter. Valve clearances were getting too tight. I'm sure this has been done, but thought I'd share...
Rather than buying new buckets to get the desired clearances, I modified the existing ones using a drill press and a small stone that is intended for a dremel. The drill press keeps the flat stone surface parallel to the "nub" that needs to be ground down inside the valve bucket. Most of mine were too tight, so this was an option. Some were fine, so I left them as-is. Note that if any valve clearances were too large, this wouldn't have been an option since you can't easily add
to the height of the bucket (reduce clearance).
So first measure all of your clearances with feeler gauges and figure out what the desired clearance should be (for example, middle of high/low specs), and record the difference
Now, one at a time, remove each bucket, measure its thickness using a micrometer from the nub to the opposite smooth side where the cam rides. Subtract from that the "difference" you got in the previous paragraph, and that will be your desired bucket height
Now place that bucket in your crazy custom bucket grinder, hold it with one hand, click it on, and with your other hand pull the drill press lever to start grinding. Just a little pressure is necessary. Slide the bucket around frequently and try not to nick the sides, but come as close as you can. Frequently mic the bucket to see if you are approaching the "desired bucket height" above (wipe the nub off first so you get an accurate result).
When you start to get close, you can wash that bucket in soapy water with a toothbrush and temporarily install it in the head. Put the cam in place with that lobe facing up - no need to bolt it down or even install the cam caps, simply press the cam down above the bucket with the heel of your hand, and use your other hand to measure clearance with a feeler gauge. If you haven't reached your desired valve clearance, go back and grind down the bucket nub more, and try again. When you get the valve clearance correct, move on to the next one, etc...
When you're done, clean everything up, oil it, and torque down the cam caps per spec. Then do one last check of all the valve clearances to make sure everything is ok.
It's all a bit labor intensive, but oh my it's inexpensive.