Answered on FB but will add here as everything gets lost on FB!
I fitted Pertronix about 4-5 years ago, never given a problem since. The model for my Delco distributor was MR-LS2.
In the UK (at that time anyway) the cheapest supply was from Retro Rockets in the US. They have a UK warehouse they ship from but the purchase is from their US site in $.
Saab 9-5 2.3t Vector Auto Estate Stage 1
Saab 9-3 2.0 SE Turbo Convertible
'81 TR7 DHC