help needed: want to fix the gas gauge once and for all

Just because a mechanical limiter sends some pulse voltage doesn't mean its correct amount/rate. Throwing a new limiter or solid state regulator in there may or may not cure it.
Just because the gauge pointer will move doesn't mean the gauge is anywhere near accurate. All of these parts are 40+ yrs old.
To assume that most owners have inop gauges is wrong. They can be repaired to work like new. Many have sent their gauges off for repair. A few of them have wasted a lot of time and money on "do it yourself' efforts first.
When you and/or the wife get tired of playing with them I'll be glad to fix them for you.
Good luck