i would stay away from the aluminum, cause your going to need to mod it anyway...you should just grab a 250R or 350X swinger or just something steel and not offset...it would just be easier....i always use steel for all my swingers and there hasnt been any major failures yet....
1985 Honda ATC250R drag trike with s/t kit and full drag CR hybrid motor and drag chassis...
1986 Honda ATC250R daily rider fully modded engine, +4 swinger,etc...
1997 Polaris Storm 800 triple, boyesen reeds, dg individual silencers, 240 studs, 123mph on radar...