HemiTcoupe beat me to it with the spacers.
I also had used a stock MII xmember that I whittled out of a pinto. Folowing an article in SR mag back in '79 ,I widened it 4 " and put it under my 31 chevy and had it all set up then Total Performance came out with the first aftermarket kit for chevy and I decded to get it and was very impressed with it. It works great and no problems so far with an average saturday rod run cruise.
What I would like to do is add an sway bar. Years ago they were available from someone that made one that mounted behind the rack. But not any more. I think CE makes a frony (stock) mounted that is 4 " wider that I will try.
Good luck, Bob.