Looking for suggestions on where to get an aftermarket barrel nut and recoil lug. Getting an aftermarket barrel so I figured I would upgrade these parts as well.

The rifle is a model 10T, SA small shank. In XLR chassis

I have seen different size recoil lugs available. Can anyone suggest a the best size for use with XLR Chassis or is it just trial and error to find one that fits the best?

Thanks