You're right, I did find that same part number on other cars, Torinos I think, and others. And while it would be fun to hunt down these old timers in junk yards, like I did in the "old days", I'm not that young anymore, and there aren't that many 60s-70s cars left in the junk yards around here (south of San Diego, near the border with TJ). So I will get by using M22 star washers glued to large diameter fender washers, pretty sure they'll do the trick.
Hey guys, catching back up on this project. Finally got to where I might call it "DONE". Of course, ran into many slow-downs along the way, not least of which was the decision to paint the entire front radiator panel - scuff, rust-bust, prime and paint. Glad I did 'cause it looks much better behind the grill and bumper now. As I said above, my drilling skills for the new frame holes were amateur, resulting in imperfectly aligned holes, with the slop in the bracket holes I was able to align the new small bumper pretty well. The '74 vinyl stone guard cut down and painted flat black looks good behind the bumper, I think, I just hope the paint stays stuck to the vinyl. Next step is the valance - either a stock piece, or modified '65 Mustang valance, still thinking about it.... A lot of lessons learned the hard way, happy to share with anybody else looking to do this swap. Thanks for all the support along the way!
