There's a ton of info on the disc conversions in the TRL. It seems that if you get the right 14" rim there are conversion kits that will work without using a spacer. Right now, I'm staying with the drum until I get the car on the road and drive it a bit.
There is also Lucas classic tires in Signal Hill. I have been to both places. I'm not to far from Performance. I have dealt with them several times.