I doubt it.
I can't post the chart because word wrap is all goofy.
Barnes 22 is recommended at 12 hp minimum, 28 recommended at 16 hp minimum.
HOWEVER, the small section is the same on both of these pumps, only the larger section is different. Once unloaded to high presure, low speed, the same gearset would be pumping about 6.5 gpm output at 3600 engine rpm. At 2500 psi, that calculates to 11.5 actual engine hp. Since most vendors (Honda included, and especially their '5.5 engine, but I assume their '13' engine also) don't produce the nameplate hp day to day, I would be concerned.
Low pressure, high speed is adjustable for unloading pressure. If it overloads the engine at say 800 psi, it may pull it to 700 before unloading.
Then, once on low speed, the only way is reducing hp draw is by adjusting the main releif valve lower. Dropping form 2500 psi to 2200 psi may allow the engine to pull it but you give up ultimate splitting force in tons.
Since they think the 12 hp engine will pull the small section when using the 22 pump, if you already have both I would put it together and try it. Just be aware there maynot be enough hp.
Since the small section is the same, if buying from new I would get the 28 pump and 15 or 16 hp engine.
If you have the parts, I would build it. If it has to adjust down to 2200 or 2400 psi, give up tonnage, I'd still do it. I think the 28 gpm pump is WAY better than downsizing to a 16 gpm pump. You will gain more wood from the increased speed than you lose by tossing a few big nasty stumps.
Must havt large enough suction and pressure lines and valve of course. 28 gpm into the cylinder rod size in retract woudl be about 35 gpm out of the closed side.
k