Not the RB383, I was talking about the 440HP's extra cost/weight negating using it as the standard 70 Bee beyond the marketing angle.
The "gentleman's muscle cars" were the RT/GTX which had a 440-4 standard and were slotted above the Bee/Road Runner. Back in 67 the RT/GTX came with a 440-4, so in 68 when introducing the Bee/RR they couldn't butt in their market, and I'm sure they didn't want to go backwards to a 413 so then just went to the 3.75 stroke 383 for the performance angle. The MSRP between RT/GTX and Bee/RR was big money at $500, or $3200 in today's dollars.
If you really want to be confused about marketing, start talking about the Charger R/T and how that even slots above the Coronet R/T because of hidden headlights.