subframe connectors questions

Hi Y'all

Im getting ready to put in subframe.connectors on my 67 cuda. I have some mild steel that is .083" wall thickness. Its 2"x3" rectangle. I was wondering if this is thick enough. The stock framerails, and transmission crossmember are this thickness. I also was concidering laying the tubing to where its 2" tall and 3" wide to clear the rear floor with minimum intrusion , and allow my parking brake cable to clear. I got the idea from bigblockdart.com, but they are using .125" tubing.i think this may be a bit thick.
Any ideas?
Thanks
Matt

I made mine out of .085 2x3 laying flat and couldn't be happier with them.
Did it for the same reasons you mentioned also (brake cable and brake line and it worked out really well.