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Have had very mixed results with the Pertronix kits. Have had one in my wife’s DD 65 Mustang for a couple decades with absolutely no problems. But had absolutely no luck trying to run one in a 65 Triumph TR4. They would fail at the worst possible times. Company would always immediately send a replacement under warranty, but could never tell me why they were failing. I finally went back to Standard brand Blue Streak points as stated above, and have never had another problem in years, go figure.
As far as my 65 Chevy, I’ve been running an HEI I bought from Langdons may years ago. Has been totally trouble free and tune up parts available anywhere. One of the best mods I’ve ever done to this truck.
For the exhaust manifold, you might want to look into a ‘big truck’ 292 3 bolt manifold. Found a repo on eBay a couple years ago that I’m really happy with. And they don’t have that stupid spring and flapper that never seems to work.
Hope this helps
Good luck with the truck
Tom