Aerostatic lift is always vertical, and doesn't contribute centripetal force in a turn. If you're in a 2G 60 degee turn, the total force in the vertical direction is equal to the aerostatic buoyancy plus the total aerodynamic lift (pointed 60 degrees from vertical) times cos(60 degrees). The centripetal force is just aerodynamic and is equal to the total aerodynamic lift times sin(60 degrees). To be in a 60 degree 2G turn you would have to be accelerating aggressively upward--for example, turning at 60 degrees while pulling up through the bottom of a dive.
To determine the bank angle required to maintain a 2G level turn with half of the aircraft's weight offset by buyancy, we have two equations and two unknowns:
Unkowns:
theta # Bank angle
lift # Expressed as acceleration, pointed theta radians from vertical
Equations:
lift*cos(theta) + 0.5G of aerostatic buoyancy = 1G # Required for a level turn
2G = sqrt((lift*cos(theta) + 0.5G)^2 + (lift*sin(theta))^2) # Setting the total acceleration equal to 2G.
Now we solve:
=> lift*cos(theta) = 0.5G
=> (lift*cos(theta) + 0.5G)^2 = 1G
=> 2G = sqrt(1G + (lift*sin(theta))^2)
=> 3G = lift^2*sin^2(theta)
=> 0.5G = 0.289*lift*sin(theta)
=> lift*cos(theta) = 0.289*lift*sin(theta)
=> cos(theta) = 0.289*sin(theta)
=> theta = atan(0.289)
=> theta = 1.29
=> lift*cos(theta) = 0.5G
=> lift*cos(1.29) = 0.5G
=> lift = 1.803G
1.29 radians is the same as as a 74 degree bank angle.
At 60 degrees in a level turn...
0.5G = lift*cos(60 degrees)
=> lift = 1G
Total G load = sqrt((1G*cos(60 degrees) + 0.5G)^2 + (1G*sin(60 degrees))^2)
Total G load = 1.32G
At 60 degrees and 2G total acceleration...
2G = sqrt((lift*cos(60 degrees) + 0.5G)^2 + (lift*sin(60 degrees))^2)
=> 4G = (lift*cos(60 degrees) + 0.5G)^2 + (lift*sin(60 degrees))^2
=> lift = 1.703G
Upward acceleration = 1.703*cos(60 degrees) + 0.5G
Upward acceleration = 2.203G
Net upward acceleration = 1.203G.