I missed the part where you said you wanted an arc not two large bends. Yeah, gonna be near impossible with MAP/Propane, and even oxy/acet w/out a jig will be near impossible to get the exact shape you want.

Get some 1" Square tubing .120" wall and have someone bend that for you. It should be about $1 to $1.5/ft. And if you have a big metal supplier near they may be able to bend it there for you. Then the fun is getting it home bent

If you were local I'd bend it for you... but I think shipping would kill that deal