Air/ fuel tuning

I'd still be cautious. Its too risky. Find a place they do standing 1/4 mile or longer and test WOT by jetting for the best mph through the finish lights. Or some fun on a chassis dyno. Start with the 82s and run by run take it down. If it starts to ping , back off the throttle immediately. If it loses mph or Hp and go back up in jetting. Also get the AFR curve - if its not flat in top gear WOT, that needs to be addressed.

Your question about secondaries effecting highway cruise. Since your 950 is customized, anything is possible. Typically the linkage is set up to open the secondaries when the primaries are 40-50% open. They should provide the same AFR as the primaries. They shouldn't be a crutch for enrichment. Their job is allow more airflow and higher pressure at high rpm.
If you want to prove it to yourself, disconnect the linkage and go for a cruise. I've disconnected them on the dyno just to see the difference AFR curves.