I know the True Ames Blade Weed, and it's a Tuttle box design if it fit your older Carve 140.
I looked at the Maui Fin Co. website to see the Weed Burner, but according to the website that design only comes with a PowerBox fin root.
The 12.5 in. Blade Weed should work pretty well on your Futura 122 I would think, but the 14.5" will work as well.
Spinout should not be a problem with with either fin, but the 14.5" suits the width of your Futura 122 a bit better.
Another fin to look at would be the Lessacher Duo Weed in a 32 cm. (12.59").
The Lessacher Duo is ver fast, and has really good durability.
Another possibilty would be a Tangent Dynamics Reaper Weed Fin in a 32 cm size.
All will work well and all of them come in Tuttle base.
Hope this helps,