I am in the process of installing a Vintage Air A/C system in my 1978 J10. After removing all of the OEM A/C-related stuff, I needed to fab a firewall block-off plate. I looked for a pre-made block-off plate for my purpose and really couldn't find a style that I liked. Somewhere out there in internet-land, this wheel has already been invented. I just couldn't find it.
If anyone who would like to have a copy of my template, you're welcome to it. PM me and I can email you a couple of pics of how it fits and what it looks like. After that, if you would like for me to send you a full-scale paper template, lemme know and I can mail a copy to you. This plate measures about 12" high and 19 1/2" wide.
In the past this forum and the ISFJA forum have helped me through lots of my FSJ woes. Maybe this is my time to give back.
Now I'm ready to put aftermarket A/C in the rest of my FSJ's!!