I'm not doing the actual valving. Someone else is. The external diameter of the cartridges looks to me about 20mm.
The CBR internals are a common swap on VF Honda Interceptors. Jamie Daugherty does quite a few of these, being the reigning expert on VF suspension. Therefore I am giving the forks to him to do the work, as he's done a lot of these CBR600F3/something else Frankenstein forks.
What I have done this far is taken apart an SV fork and a CBR fork. I suppose I could just put them back together and guess that the valving will be OK. From the racers I know that have used CBR fork internals they have really excellent valves and the damping should be close enough, but since I had them apart... and it's November in New England.... I thought I'd send them out for an expert to look at.
The CBR internals are also a common swap for some modern Triumphs and, I think, the Versys and the
Honda Hawk. The Hawk guide is pretty much the same for doing the swap on the SV. I haven't found really great information anyplace on the web but it's plain as day when you take them apart as to to how they should go back together. If you are at all mechancial you should be able to do this.
F3s are getting pretty long in the tooth, so you could pick up a set cheap, this is a whole lot cheaper than doing any other real surgery to the bike besides Race Tech emulators, which actually work pretty good.
This swap will add both rebound adjustment and preload adjustment to the fork in one move, along with true cartridge damping.