The honda CB is best. Plug and play! However, others can be made to work. Valkyrieblingandmore.com adapts Yamaha CB's to work. He changes the plugs and wires. He also uses a Y, so that you replace the standard radio antenna, and Y's the CB and radio together, to use just one antenna. The OEM CB uses a seperate antenna, which is probably a little better.
Go for the IS! The Valkyrie is a great bike. I have a 97 Standard, which you can see in my Avitar, although it now has IS hard bags, and a trunk, painted to match, on it. I should update the pic.
I also just bought a 2001 maroon/black IS to put a Hannigan sidecar on for my wife. I have posted pics of it on a thread.
I always like my 2003 HD Heritage Classic, 100th Anniversary model, but I sold it when I was running semi all over the US, and never got to ride it. When I went back to farming, I wanted another bike. Actually, I NEEDED another bike!

I bought the Valkyrie, and like I say, I LIKED my HD, but I LOVE my Valkyrie! Very good bike, draws lots of attention, pisses off HD riders, because in a parking lot of 100 bikes, 97 of which are HD's, 2 others, and my Valk, my Valk draws the crowds! LOL

Go for it, you will NOT regret it.
MP