As someone who is currently upgrading an RC model that is of similar size as this B1, i find it highly unlikely that a fully built up model would fall below the 100# LMA max for a turbine powered model and be structurally capable or withstanding 8+ g's. My 1/4 scale project has shown 8g's in a 60* banked turn at a moderate 120mph flight speed to keep it within the boundaries of your average size flying location. This is a model that is basically a round-e-round model that isn't exposed to aerobatics. On this project of mine, i have made significant use of molded fiberglass components where structural necessity is not required and fiberglass reinforced lite-ply structures with significant lightening and all i was able to shave off of one component is right at 15 pounds.
This B1 as drawn, IMO is significantly lacking in many structural area's (specifically the wing pivot, pivot box and H.Stab structures). Then we bring in the complexity of the swing wing and the H. stab pivot locations, both of which look to be improperly positioned, especially the H. Stab pivot. I am tempted to purchase a kit just to try one, but without an available source for landing gear, that will not happen.