I've been trying to get rid of nock high with bare shafts to no avail.

Shooting 3 fingers under
Tried nock point 1/2" as well as 5/8" without success.
Tiller is 7 1/4 on top limb and 7 1/8 on bottom.
Shooting 64 inch recurve with 36# uukha alpha ILF limbs at my 28" draw
Brace height is 8 1/2"

Suggestions gratefully appreciated.

I too always get nock high when bare shaft tuning. I never worry about it too much as long as it's not crazy high, if your arrow is sticking in the target almost vertical then I'd say it's something to do with your release/finger pressure.

Put feathers on and see what it's doing.

Too much FOC can make nock high hard to tune out on a bare shaft??..have you done any experimentation with nock tension? (how tight they fit serving)..You could try moving one string silencer a long way so they are unequally spaced from limb tip (if you are running any) just ideas..You might try 1"  nock point  height..and work backwards..to prove you aren't getting nocks high from bouncing off shelf\rest from being too low..work the problem from way too high back down.. I only use tie on points..and screw them up or down the serving to adjust slowly..I've never had good luck with crimp on nock points..ever.

I'm not a 3-under shooter, but can offer suggestions......

First, I'd recommend you adjust your tiller bolts to even tiller vs your 1/8" positive setting.

Next, use 2 nock points (1 above the nock and 1 below) and don't have them tight against the nock--leave a bit of wiggle room.

Last, start with a 3/4" nock height and work down.

Good luck!