maxima 927 is great but its expensive if your racing then its the only choice but for just tooling around or riding with friends i run amsoil dominator in my '77 PE250 at 32:1 as does my friend in his '74 TM125 it seems to work well on the old bikes and its a bit cheaper than the maxima stuff
Its good to see that more people are riding the vintage bikes, Good luck!
I do know 1 sunoco station with in 20 miles, and its under cover. The dial a octane, man are you old! Torco dealer in Valparaiso, In., or Dr. Dave in Bensenville, Il., have the stuff in 5 gallon sealed cans, no under ground leaky tank car gas for the race bikes! Man I remember burning up a lot of top ends running that gold label blendzall, nitro additive indeed!