sure why not... after all no one's gonna measure it's specific gravity, so skip the details and just have it fuck you up a lot.
suggestions:
1. methanol. stronger than ethanol. causes blindness.
2. 95% or absolute ethanol + a benzo of some kind. fucks you up. may cause sudden death, but at least it's not methanol.
3. ethanol - ether. a proper mix of even 95% ethanol with enough diethyl ether might even *look* like it was 245 proof if you were measuring specific gravity. it would fuck you up to unholy extremes. it would taste awful. might kill you, i'm not sure. highly flammable.
proof is a dumb idea (i live in a % alcohol area, and no one is gonna believe 120.5% alcohol =)).. you mix the alcohol with gunpowder and if it burns, it's over proof, if it doesn't, it's under proof.