Hi,
Personally because I'm cheap,LOL. I'd try to locate and clean up/rebuild an original. You can use one from a 67-70 they will all interchange no problem.If you look around on Ebay,craigslist,etc. They can be found and especially swap meets. Brand new units are available, so that's an option as well. Good luck.
P.S. I responded to your ad in the classifieds, if you do swap to a 9 inch,and you are selling your 8 inch,Let me know, I know someone who might be interested.