There's not much for frames in the $600 range with the options you want. You could look into a Redline Flight MonoCog frame that has sliding dropouts, or you could do a Vassago Jabberwocky with horizontal dropouts and the ability to run Vassago's gear plug kit to use a derailleur.
The scandium Niner One9 is on sale at speedgoat.com right now for $600 instead of the usual $800. It comes with EBB. Not sure if it can be run with gears.
The Flight MonoCog is sort of short on the top tube, the Vassago a touch longer, and the Niner a touch longer still. You'd want the XL in all of them.
The scandium Niner One9 is on sale at speedgoat.com right now for $600 instead of the usual $800. It comes with EBB. Not sure if it can be run with gears.
The Flight MonoCog is sort of short on the top tube, the Vassago a touch longer, and the Niner a touch longer still. You'd want the XL in all of them.