Shooting black widow recurve 54lbs at my draw 29 1/2" shaft 100 gr brass inserts with 125 gr points wanting to shoot axis shafts what do you recommend. Thinking 400 spine not sure if I need the 100gr brass inserts, but would add some foc. And weight  to the arrow for hunting

400s should work great.  My Elkheart is 52@29 and I shoot full length Axis trad .400s (31") with a 50-75g insert and 125 tips to outstanding effect.   With 400s and 125s you'll be in the ballpark and you can play with insert based on the brace height you shoot etc.  you should be able to go 100g for the extra 25g no problem and just tune the bow to it.

Yep.  .400s will work fine, and keep the 100 grain inserts for the FOC. Vary the adaptor and point weight to tune to your bow.