Couple of things - as reflected in another thread here - I've heard that a large/heavy bunch of keys can cause issues as it put undue strain on the internal mechanism.
If you have to replace the ignition barrel, have a look at MGB ones - I replaced mine a few years back and the MGB one was virtually identical and a fraction of the Morgan price.
Getting the old one off can be a little tricky, but I drilled and snapped mine out - if you get to that stage let me know and I'll let you know what I did.
This, definitely. I replaced mine years ago with an MGB lock. I cut the old one off with an angle grinder.
The other thing to do if you're able to keep your car in a garage or somewhere safe is to not break off the bolt heads when you install the new lock. They come with intentionally weak bolts, the idea is that the heads break off when you tighten them up, thus making it hard for a Ne'er-do-well to remove them should they want to nick your car. I left mine as is to make it easy to remove the ignition lock should I need to. But having said that it must be at least 15 years since I put the new lock on and I've not needed to remove it again.
