seth,
I actually turned down another free bike today. A 90's kawasaki vulcan shaftie that had seen better days. About the only thing useful to me off it would have been the front end (lester looking front wheel, modern single pot calipers, and dual discs) which I could see had a pronounced bend in it (probably from being dropped). The bike was around the corner from me and the owner threw it out in the street (literally on it's side) to be picked up just as I was walking by. Still might go back under the cover of darkness when the GF is not with me.
Nice compact single pot and dual disc setup, might be adaptable to your existing setup.
on another interesting note the ex500/zx6 calipers I have been expirimenting with take a 5mm thick rotor. If your cb450 rotor is thicker than this we can turn it down, if thinner we will have to find another rotor (cb750?). I have brackets made up for the cb750 and the h1 coming in from texas, if you bring your bike over for me to get measurements I think I can have a bracket made up for the cb450. Once new caliper off an ex500 will lock the front wheel easy. I spoke to a triple racer in NM and he tells me the dual ex calipers he was running was overkill...found he was locking the brake with two fingers going into almost every corner, with one brake he has much more control. with your cb450, one modern caliper should be all you need...plus nobody will ever spot it because most NYC motorcycle people don't look that close.