No gasket needed. 1/4" is a little more than usual, but it will still do fine. In your steam stack, have a damper. To regulate the steam flow, start closing the damper just until some steam starts to escape thru the gap, then open it very slightly. As the boil rate varies you might need some tweaking on the adjustment. Hoods do not fit tight, they just set on top. Most have gaps but they are generally a little less than 1/4", but that will not be cause for anything radical.
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.