Also, what size do you have your wood split at? Is it essentially wrist size and it the wood dry?
Any squirrel cage blower I've seen with just a 2.25 inch round exit is way too small to feed that arch. You need more air.
Rather than that blower you will likely do better just using the vent door, under the grates, open it up at least 6" and see how that helps. That along with the wood dry and split to wrist size will do it, because your stack it tall enough for that arch.
The space under the flues should be about 1/4" to force the heat up thru the flues.
Dave Klish, I recently ordered a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.