A good point Derek.

Several things,

1. One of the heads is not on an Austin Seven and, although I have spare for that car, it is not the 'correct' head, I would want to change the head gasket as well.

2. The Austin Seven head is not a low compression head, by any means, and is on a rather special engine.

I am loath to disturb the heads on engines that run perfectly and have done so for a very long time.

I am very happy to give some to the recommended stuff a go but do have alternatives, as you suggest, if it proves unsuccessful.

Hey R
I have had great success with Ce-lit

Location: The Centre of the Universe

The locals won't forgive me if I don't mention JB Weld (longer setting version) after usual cleaning and wedge groove in crack. I've fixed many things...list too long to mention and even cast small unstressed bits with it. Although apparently, much to my horror and loss of credibility it has been in a recent competition with Loctite Steel (and others) and was found to be inferior!

Location: Ferring, West Sussex

Well I had to ask.
I didn't have any joy with K seal on the Rosengart block hence it got chucked and another found.
Good luck with your endeavour.

Location: Oakley , hants