Terminating Pyro cable

I am being asked to re-terminate some pyro cable because of a broken cable and replacing a diy joint made with electrical tape, not something I have done before. Watched some videos and the process doesn't look too difficult, will get some materials to practice with first.

Now some questions  

The cable is 50 or 60 years old, therefore presumably an imperial size with cores close to 1mm, I can get a micrometre on them if the job goes ahead. Can I use a metric size gland close to the imperial size. Alternatively the gland is marked L238, I can find RGM238 glands, cable pots etc  on ebay, presumably more or less the same thing. This is for use in a church, so not hazardous but damp.

I am looking at also buying suitable tools on ebay, kits seem to go for £50 to £90 for used, looking to save money and finding a new imperial pot crimper would be challenging.

Appreciate any advice or tips that can be provided.