I stumbled across this site for battery cables, either a preset size or custom can be ordered. Seems like a good price for high end cables and trminals. I will probably use them when I relocate the battery to the storage bin.
http://www.pa-performance.com/display.asp?sku=74
they also have some compact alternators that look like they may work in a RX-7.

 

I made my own cables for a fraction of the price they're charging. Just go to your local autoparts store and buy the cable and connectors, and make them yourself. No real special tools or experience necessary. Just remove yours and bring them in for comparison. Buy wire of the same gauge or larger (and I got mine in copper for better conductivity), and buy similar connectors.

I did the negative cable in two segments because you can't find replacements for the stock connector Mazda gives for the strut tower. It works well.

Jon

 

The NAPA stores can get standard type lead terminals that are precharged with solder and flux. This allows you to make a very corrosion resistant connection to the cable. Basic, but it will "git-er-done". The PA-performance terminals are compression type, nicely finished and have provision for smaller feeds to the fuse box and to the sound system and 12 v power outlet. Great appearance and solid connections. I have seen similar terminals at stereo installers for $20- $35 just for the terminals. If you buy the individual components of equal quality, I doubt you could beat the price.
YMMV
Dennis