I don't consider that a delay, Paul. I admit I get a bit testy when we get to this point and the other party suddenly vanishes forever without an outcome, so the whole exercise is wasted, but you are a model of cooperation and a genuine pleasure to work with.
I think either epoxy cement (araldite) or cyanoacrylate glue (superglue) should be strong enough for this job. To use either of them you will need to get the cam lobe clean, without damaging it. Acetone would be a good cleaning agent. Carburetor cleaner will degrease it well but leaves its own residue, which might be a problem. If you have isopropyl alcohol it should do the job. I think I'd give it a short blast with carb cleaner, then dry it with a clean cloth and do a second wash with methylated spirit. Remember, you only have to clean a very small area. After the test you'll need to remove the glued-on bit and oil the cam right away, or it will rust.
A one-piece bump would be better than a multi-piece one because with multi-piece you can't be sure it doesn't compress when the load is on it, due to the spaces between layers.
