I would start with a low memory usage ROM.
http://forum.ppcgeeks.com/showthread.php?t=118668
This one uses far less memory than the 6.5 ROMs, and it still has the awesome YouTube app. Even with the massive 24 MB PP I still have 52-46 MB free RAM to work with.
P.S. Cranking down the Page Pool to 4 MB is suicide for speed. Opera Mobile 10 is a dog at even 12 MB PP. And no, 0 MB PP does not do any better.