As none of the published Pontiac wheel code charts seem to be completely accurate, why not create a chart of our own?

I'll contribute two right now.
JA 14 x 6 Rally II 4.75" bolt center 4.25" backspace 2" center bore
JC 14 x 6 Rally II 4.75" bolt center 4.00" backspace 2" center bore

If you're not familiar with the terms, the methods to measure can be found here: https://www.rsracing.com/tech-wheel.html

Boy that link spells out just about everything about wheels.

JK 14" x 7" Rally II 4.75" bolt center 4.50" backspace 2" center bore

IF 14" x 7" stock steel 4.75" bolt center 4.50" backspace 2.75" center bore

A note about the IF code wheels. These are the wheels that came with my conv when purchased. I don't know if they are correct code for '69 but they are the correct dimensions. JK code Rally II are correct for '69 Firebird, GTO and GP.

Could you please double check that center bore on the IFs? My 2nd gen rims are 2.25 center bore. I'll be adding three more sets to the list.

Vikki, I broke out my inside calipers out of my tool box. I verified the center bore on these wheels at 2.75"

the ja and jc's are for 68 firebirds right? and 69's with 6 cyl?

I've used this chart a few times.

http://www.pontiacserver.com/wheels.html

That chart's not all right. Nor are the service manuals. And with all the changes made to cars over the years a spec sheet and a requirements sheet would be more useful than a list of original applications, although that is needed as well.