Morris Minor Owners Club

I want to buy one of these on t'internet but not sure which one to get. I have borrowed one in the past and it was the wrong size (too small to fit around the head IIRC) so can anyone tell me which one to look out for?

The smallest one from Machine Mart will do the trick- it worked for my car when I replaced an exhaust valve and re-lapped the rest.

thanks john