With regards to pre-heating:
The Civic CVCC
https://www.thedrive.com/new-cars/1974-honda-civic-cvcc-review-drive-history-price used a (third-valve small richer chamber) to ignite the (larger) lean mixture. Lean burns hotter so this was perfect for the bottom of the stroke. It used any kind of gas with no cat and got great mileage. My dream car as well.