On my evaporator I get 23-25 gal of syrup/cord if running 2% sap. A block arch, depending on design and such might get 8-12 , maybe less. On a block arch there's far too many variables to guess closer. Is it insulated, what is the height under the pans, is there a front door of some sort, do you have it built with a stack? There are many other variables too.
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.