Hi Mike (g4wam), first off I cannot see where the thread is worn out, it looks fine to me
OK with regard to the jacking points on the MK2. I have just nipped out and photographed mine
Here it is from under the front of the car looking up, it should be just behind the bumper
It is also visible through the lower front grill
Thank you for resurrecting this thread, I have never read it before and never new that these small bits of metal were in fact jacking points
Having known nothing about them I cannot realy answer your question, I would however imagine it is possible to have one welded on if it is indeed missing from yours, but hopefully someone will be along very shortly to give a definitive answer.
Funny this should come up now as we have just had a question in the MG T-Bar Quiz about jacking up an old MG, an MG Y-Type. Take a look at the fancy system that old thing had,
click here to view