Whats the best way to detect knock and retard timing with gm hei

I want to use gm hei without an msd box. Its street car and had bad luck with msd on the street.

I want to use gm hei and have an knock detector that can show a warning light and also pull the timing back even if it pulls it way back. One degree or even half steps would be best but not really worried about mantianing power as much as dealing with a single crap tank of gas without smoking the motor.

Lots of traffic and bad gas stations with crappy old tanks and owners that will do anything to save a buck. Actually seen the citgo truck filling the tanks in an exxon. I now its all the same gas from the same plant but still too many corners being cut to trust it. Getting 87 from all three pumps is not unherd of.

I have seen several warning light systems for off the shelf knock detectors. But looking for something a little more professinal and not away from the original hei. Since it works fine for most chevy builds. It would also be nice if the system was brainless so i could put it on engines that are not for me personally. Keep brainless people from killing a motor with a bad choice in city gas stations.

This is for a high compression natural asperated chevy 350.

Any helps would be greatly appreciated.