> it's dual core which makes it less appealing in a MorphOS context

Its FPU implementation makes it even "more less" appealing in a MorphOS context.

> e500 cores (what used to be "G3")

No, e500 is neither derivative nor descendant of MPC7xx.

> If you want e500 there are a few other SoC's in the PowerQuick line
> of products that would perhaps be more suitable in a MorphOS context.

Unfortunately, there is not one single e500 based PowerQUICC (III) SoC that is suitable in a MorphOS context (see above). The first e500 based SoC that would be suitable will be the upcoming QorIQ P4 sub-family with its e500mc core (and with P3 and P5 following).
PowerQUICCs suitable for MorphOS are the 603e/G2_LE based PowerQUICC II and the newer e300 based PowerQUICC II Pro families.

> The 8610 is possibly the best performing 32-bit PPC implementation
> that was built by Freescale

Nah, that would either be the 8641(D), which you mentioned, or the 7448, depending if memory speed or core speed is considered more important. And btw, *all* Freescale PPCs are 32 bit ;-)