I started like you did, use an estimated 2.3 times the surface required for gasoline...
The supercharger calcs. I devised/used to make my engine gave me a ratio of 0.6 litres of methanol per mn at 5500rpm.
I also did another calc. by extrapolating the known jet I used on a 175cc OHV racer I had that also ran on methanol.
Same results...
But once on the Salt Flats, it all went through the window!!!
Be also prepared to increase dramatically your float chamber volume.
A 70's S&S MGAL chamber can hold 175cm3, it proved inadequate...
Our fastest run as above used about 2 litres of methanol for 2 miles in just 1mn and a bit.
I'm not too sure if methanol, ethanol or alcohol will all like the rubber bit on your inlet needle???
A bit of weight there like on mine might help your sealing problems. You can also see that I made the valve body with more thread, this to raise or to lower the level in the float chamber, useful since I wasn't sure of the methanol density at the Bonneville elevation.
The pistons I use, std cast K Model "Superior" Dixie, got a bit hot when I was running that lean, but nothing too dramatic, they were reused untouched...
Personally, with the std jet calcs that relates to sea level usage, I thought I would be way too rich at Bonneville elevation with less oxygen and less atmospheric pressure...
The contrary was actually true!!! Strange...
Patrick