I you can do that, you will become a PowerPC rockstar.
Combing through all of the Geekbench benchmarks, the 2.7 beats out the 2.3 by 200 to 300 points, which makes the 2.7 I'm typing on feel warm and fuzzy.
As for the App store, there are a few things you may want to check out. One is MacLibre. It had free software for Macs. I believe it connected to a server and retrieved a list of downloadable apps. It does not work anymore. Please, don't take any cues from the interface though, it is poor. The MAS interface is pretty good, something like that (perhaps more lightweight) would be good.
The other thing to check out is a website that is being set up right now by 2 members of Macrumors (myself and spyguy10709).
There is nothing online yet, but I have gathered and collected about 200 pieces of software that I will be uploading very soon. It would be very cool if your App store could connect to the webserver, get the descriptions, authors, date released, compatibility, display it in a beautiful Mac App Store interface, and offer it for download.
Nice new PPC site, Can't seem to create a login though -- got an error. Thanks!