Beautiful scans, Rao! Just a little clarification for those who didn't get Solo #1:
The top illustration at
http://superman.nu/supergirl/costumes/2004/ isn't the new Kara Zor-El that debuted in Superman/Batman #8 (though it IS a 2004 picture), nor is it REALLY the Silver Age Supergirl. Solo #1 (featured artist Tim Sales) had a Diana Schutz' tale, "Young Love", that explored what happened after the suddenly-cancelled (The Daring New Adventures of) Supergirl #23 left a tantalizing cliffhanger with Linda Lee Danvers and the suddenly-resurfaced Dick Malverne.
It was nice to see that dangling plotline finally resolved after twenty years, but that presented a stylistic problem. While this definitely was a pre-Crisis Supergirl story, it might have been too confusing to cram all the appropriate appearance changes into just eight pages. (This tale is told in retrospect, so Kara would have been seen in at least three different Supergirl costumes.) Tim Sales decided to keep Kara "fixed" in one look -- a "traditional" Supergirl costume with a red skirt (unlike her original all-blue dress) and a short hairstyle. So yes, this Kara is technically inaccurate, but she's a perfectly acceptable compromise given the situation.
I'm absolutely delighted that this tale was published AT ALL (considering DC had long insisted that Kara NEVER existed, but at the same time Solo #1 was published they were loudly proclaiming the debut of the NEW Kara), and I'll accept this as "canon" regardless of the artwork descrepancy.