The whole "Patina" thing is a personal choice, a little bit of surface rust here and there, some paint fade, that's fine. When there's more rust than paint though, any reasonable person would want to make it look nicer. I hate over-restored show bikes that are trailered from bike show to bike show by boring old farts who only ride their bikes from their trailer to the show and back to impress like minded boring old farts who aren't motorcyclists, they're investors.
Having said all of the above, Sandcasts are in big demand, and worth big money. There are folks with deep pockets who are more interested in owning a shiny over-restored status symbol than a bike with some history. I have to laugh when I see how these things have gone up in value, I bought so many CB750's for less than a dollar per cc, (I paid $300 for my K1 in 1980 and the seller threw in a K0 as a spare) and nowadays they've been put on a pedestal by "collectors" (investors) and the prices seem to go up every time I see one for sale.
If it was me I'd get the frame blasted and paint it with rattle can paint (2K and powdercoat wasn't around when out bikes were built, and doesn't look anything like the OEM cheap arse paint that Honda used, I know, I bought my first CB750 new) clean up the chrome if possible, or have it re-chromed is necessary, and sympathetically restore the paint and plastics. It'll still look like a patina bike, but will be still very desirable. But if you're building it with a mind to selling it John, then go the whole hog and do the Vic World thing, as much as I don't like show bikes, there are plenty of people out there who want a brand new looking sandcast.
