I tinkered around, shot some club matches, then found out wife was preggo a few years ago.  Sold the rifle.  Now have time and am within easy drive to a few places with real matches.  I want to turn a spare lower into a service rifle. I was A2 before all the 2016 changes.  I want to use the optic, so that is the route I am going.

1. I see a few mentions of people using MBT-2Ss.  They are advertised as 4.5lb pull... I don't have a gauge. Do they work/meet the requirement?
2. A few matches I like to shoot require irons, so I will potentially want to swap a carry handle NM rear on and off.  White Oak A4 upper and pinned NM Carry Handle the way to go?  I obviously will need a QD cantilevered optic mount that locks up.  Any suggestions here would be appreciated. Is it a realistic expectation to be able to do this?
3. I have never used the UBR stock before, but the LOP adjustment seems like a very nice thing to have.  Any downside?
4. 1/4 MOA adjustment 1x4 is obvious way to go.  I don't want to drop 2K on an optic.  Some of the $500ish Leopolds seem like a strong option...

Anything I am missing?

I’m new to the sport but really enjoying it. the optic I have a leupold 1.5-4 freedom AR scope.
At less than $300 it seems like really decent glass. 200 yard zero on a 1.5” height, zero m.o.a. mount is only two mills above nominal. Another 4 mills up for 600 yards. Not even close to maxing out elevation.

The UBR gen 2 buttplate sucks. I think the bolt pattern is different from the gen 1 so you can't just swap, and the they don't checker the plastic underneath anymore so you can't just remove the plate.

I wouldn't mind non-QD mounts, but nuts with a screwdriver slot are nice as a knife spine can be used to remove it. An LPVO requires at least 2" of cantilever, more likely 3" (from front of base to rear of fore ring).

The MBT should, maybe with a little trigger spring bending. If not, put the heavy spring in.

What matches near you require irons?

Its a fun match, not for keeps.  I could just get a cheapo A2 upper and use it.

I went and got a UBR 1 a year ago, then I had to get a carbine spring and buffer.  Did it change my shooting or scores? Nope.  The UBR 1 is fatter/wider than the A2 stock, so it feels different under the cheek.  I'd save your money on the stock and use it to get better glass and mount.