Best approximation would be to look at the drawbar pull section at at 50% load (64 hp) and 1561 rpm, it used 5.1 gph. Now if you look at a 2-105, at pto speed (2300rpm) and 71hp, it consumes 5.3 gph.
That's not a perfect comparison because we are comparing a drawbar test to PTO test which gives an slight unfair advantage to the 2-105 (less driveline losses through the PTO vs the transmission).
Bottom line, you are not going to save a whole lot if anything by buying a 2-105.
And if you are worried about wearing out a clutch, put in a kevlar one from Southbend. Best bailing clutch out there in my opinion.