I believe you have made a major error right off the hop, more on that in a minute. It's fun to extrapolate from all the powder handbooks and reloading manuals, but computer modeling might be the better answer and tell you some other things that are useful like amount of propellant burnt and the shape of the pressure curve.
From experience in a whole bunch of cartridges it looks like your Universal prediction is pretty close. Clays is a little low and Win 231 a little high, it's actually about like Universal in smaller cases. If you can meter 2.5 grains of Clays Taco Shells reliably you're a better man than me.
You're playing in the 9-16K pressure range which is definitely Unique or faster territory unless you have a much heavier bullet or far less case capacity.
About the error: Your target with the 38.5 grain NOE bullets and 4.0 grains of Unique has 1744 fps written by it, not 1400. This agrees with Quickload vs. 6.0 of 2400 and your velocities, proportionately but not exactly due to me having to extrapolate things myself not having bullet length, seating depth, case capacity to overflow in grains of water, etc., and I can't remember what your barrel length is so I put in 24". You also lose some velocity due to leaks without the gas checks.
What I get from QL with default data and Lyman 37-grain bullet:
Clays, 2.5 grains, 1,573 fps @ 13KPSI peak pressure, very spikey curve (pressure peaks at 1/2" bullet travel).
Win 231, 1,780 fps @ 12.7KPSI peak pressure, peak at 1" of bullet travel.
Universal, 3.2 grains, 1,705 fps @ 10.5KPSI peak pressure, peak at 1.2" of bullet travel.
Unique, 3.3 grains, 1,709 fps @ 9.3KPSI peak pressure, peak at 1.2" of bullet travel but curve falls off more slowly than Universal, which is how the two always compare. Plus the Universal will always burn more cleanly.