The rimblow you describe is exactly what came on my '71 Swinger. Has the black rim inside the wheel that would have been to honk the horn. Hard now and the wire connection is gone off it. Resto is a bit expensive for me so not considering that at the moment.
Not sure on other A bodies, but the rimblow was an option on the '71 Dart. Think it perhaps became available in 1970, but don't remember. Code on the car is A61 which gives it the Automatic Special Package. Gives it auto trans, outside remote mirror, belt mouldings, rimblow horn, vinyl roof, bumper guards, white walls, deluxe wheel covers and vinyl side mouldings. Supposed to be the same wheel that was used on the E bodies, but don't have any info on that.
Just wish mine worked! There is someone restoring them that posts on another site, but if I remember correctly they run around $300 to $500 or so to restore. Too much for me!
Cheers