Go by the BTU ratings. The finisher Leader makes at 16" x 34" has 2 burners @ 60,000 BTU each. For a 16 x 24 you may want a total of about 70% of that, or about 84,000 BTU total/2 in about 42,000 each. When I had a 16 x 4 finisher I never fired it at max. so you might be good at a little less. If it is too big, you can slow it, but if too slow you can't turn it hotter that it's design BTU's. I would suggest somewhere between 2 @ 45,000 and 2 @ 35,000. If you look at Agri Supply they offer several and each will either come with a regulator or will specify which is needed.
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.