Back when I had gas powered vacuum pumps I had 2 systems on them, each about 750 taps at times. I used Honda engines. The 6.5's did ok, but I then swapped one out to a 9 hp and it used less fuel on the same system. You will want to set up with a larger gas tank than they come with. I hooked 2 @4.5 gal tanks together. You will likely need a 20 gal minimum. How will it be hauling fuel in? One of mine was just 40' off the road, the other was 950', up about 15', then go thru a boggy swamp for the last 350 feet. No way to haul it in when the snow got deep, I carried 2@ 2.5 gal each for a balanced load. No snowmobile at that time, when I got one later on, it often couldn't handle the deep snow, on snow up to about 1' no problem., deeper with big drifts no way.
Dave Klish, I recently bought 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.