OK, now your dilemma makes alot more sense.
I'm pretty sure that the Futura 122 is pretty close to 122 liters, but the "volume
distribution" will be significanly different than your SP II Bombora.
The Bombora is 292 cm long and the Futura is 244 cm long and 76 cm wide.
So, you will indeed need to make some "adjustments" to your uphauling technique.
The volume in the Futura 122 is going to be significantly further back in the board, so
if you use the same "positioning" (relative to the mast foot) the Futura is going to sink by the nose pretty quickly.
If you adjust your "positioning" further back on the board to get your center of mass over the center of actual volume, you may find the Futura doesn't sink on you.
Also, longer narrower boards were/are not nearly as sensitive to fore and aft sailor positioning as the modern wider/volume further back boards like the Futura.
I would encourage you to sail the Futura a bit more and see if you don't find that once you make the technique change to get your weight back over the fore/aft center of volume, you will find the Futura does indeed have enough volume for a fellow of your weight.
Once you get the positioning sorted, I think you will find the Futura does everything your Bombora did, only more easily.
It's really OK for the board to sink so that just the tip of the nose and tail are out of the water.
The additional width should make uphauling far easier once you get the fore/aft position
I found exactly the same thing with really short boards like the Hypersonic 96 and the Compact.
They felt terrible and wanted to sink out from under me (even though both had plenty of volume) until I made the adjustment and figured out that fore/aft "balance"/positioning was actually more critical on these boards than side to side (athwarships) trim and positioning.
Once you get the rig up and the board moving forward I think you will find that there are no volume issues and will most likely find the Futura to be a really nice, fast, easy to jibe and easy to sail board.
Just try to change your "focus" from "side to side trim" to focusing on fore and aft trim.
Hope this helps,