^^^
The Slant Six was to solve a packaging problem...new styling/design-language expectations required lower hoods. New expectations, plus competition, required overhead valves...up to this time, Chrysler used a flathead six. The flathead lost a lot of power, and had cooling issues...that's all flathead engines; part of the design compromise. What it offered was a low height and simplicity.
So they tipped over their new six 30 degrees. There were actually some doubts that buyers might accept it - the idiot press wondered if pistons not straight-up-and-down might lead to wear issues (ignoring 30 years of V8s and the new Volkswagen engine with pistons horizontal). But it did gain acceptance, and then awards.
It had potential for racing...unusual for a six like that, a heavy engine - but what kept it in production until 1988, was...RELIABILITY. Long, long life. Designed for a compact car, it found its way into Dodge trucks, and became a mainstay.
And Chrysler lost a lot when they pulled production of it.
FWIW, the K-car engine made by Chrysler, was a Slant 4...not the same basic design, but they did tip it over to fit. By that time, priorities were a bit different at Chrysler, and that engine was not overly strong, nor renowned for long life (but far sturdier than the crap they make today). Chrysler learned a lot, back in the 1960s - unfortunately the lessons are lost, with the Daimler takeover and gutting, bankruptcy, the political gifting of Chrysler to Fiat, and now, Fiat's being merged into Peugeot, to make Stellantis. The Brussels management cares nothing for long life or value delivered. They're Woke - they want to make cars' operational lives SHORT, so that the Poor don't get them as used cars. Because poor people must not have cars - because, CLIMB BATE CHANGE!!