i would talk to schnitz (they deal adams and macintosh), spencer, and thompson.
i ordered my 6-10 pro moly pc flat black, nos and air, underbraced, it was like 1400. gets rid of the oe style brake mount, and uses gen 2 brake parts.
have you looked into that guy, canadian mike? or something like that. a few people praise his arms. they seem to be priced low.
im pretty sure last time i checked, adams, macintosh, spencer all could modify your stock arm and stay under 1000 with underbracing.
a full aftermarket arm can be had without under bracing for 1000, but the underbracing throws it over in most cases.
hope it helps. just trying to pass along some info i found while purchasing my arm.
btw most moly arms ive seen use 4" adjusters. dunno if they can be had otherwise.