I had the hardest time finding a vert bar to suit my needs with my LDCs, having enough clearance between the two mounting posts to run them head to head. .Below is a modification to the Shure a27m vert bar that will allow plenty of clearance.

you need the Shure a27m vert bar.
http://store.aiconsol.com/a27m.html
you will also need a coupler from fastenal...
http://www.fastenal.com/web/product. ex?sku=0148071

Fastenal Co.
Part # 0148071
1/4-28x7/8 COUPL Z

get a female coupling and piece of threaded rod.( the sku on the threaded rod.=0152183)

screw the female coupling to the top of the a27 bar and thread your piece of rod into the other end...bam, problem solved.

Also grab a piece of pvc pipe and paint it black to cover the exposed thread and maintain a professional appearance.

Teddy