I am looking to upgrade(ie more than two forward gears

) the tranny on my recently purchased 67 RS running a stout 406 sb. I have gone from a built 700R4 to a 5 speed manual to a 6 speed manual in my head. Now I am debating adding a gear vendors unit to my built power glide. The price is around $2500 +/- for the shorty unit. Is anyone running this combo?
Thanks in Advance!!