My roll bar is an old Holbrecht unit. It was SCCA legal in the '70s,
but rules have changed. I suspect that some of the bars listed in the
catalogs are the same or similar designs, you can always ask and see
what they say. IMHO the "appearance only" is a legal disclaimer.
I had a local circle track car builder add a diagonal brace, and a
horizontal bar for harness mounting. This is my autocross bar and it
still allows the top to be used.
Whatever you do, remember that the roll bar is probably harder than
anything else your head is likely to hit. Good padding from suppliers
such as Racer Wholesale is pretty inexpensive, and adds to the
"appearance" of your roll bar.
Life is too short to drive boring cars!