I picked up an old Ben Pearson Colt (semi-recurve). Bare shaft tuning is giving me fits. Arrows seem spined well (no left or right tears), but nock tears high no matter how much I move nocking point up or down. Best I can get is nock about 4" to 6" high at 20-feet (with a 1/4" high nock point). Tried shooting off-the-shelf and with elevated rest--no improvement.
Should I just fletch the arrows and not worry about it?
I've tuned a few longbows, never had a problem like this.
Any advice is appreciated!

If you're nocking under the nock locator, 1/4" would be way too low, in most cases.  A 5/16" arrow would be slanted uphill to the arrow rest, for example.  I recommend that you start too high, maybe 3/4", and work your way down. If there doesn't seem to be any reduction in the nock high as you work your way down, then it could be that there is a tillering problem with the bow.  If there is a reduction in the nock-high as you lower the nock point from 3/4", then set your nock point for wherever the nock-high stops diminishing.  I assume it's not your release that's causing this problem, as you say you've tuned arrows successfully before.  

If none of this works, and you just want to shoot the bow, then set the nock point at 5/8" and forget about it.

Do you shoot three under or split?  If you shoot three under then try a double nocking point (above and below the nock).  I had similar problems and this got rid of the high tare for me.  Hope this helps.
Aaron