Having just recently finished Avalon myself, I think that you're in a pretty good position at this time. However, a few extra levels wherever possible can never hurt!
I just entered the wyrd and I am a level 77 half way to 78, am I underleveled or at a good level?
You're good. The level you're at now will put you at level 82 or so when you get to Azteca which is 2 levels above the recommended level for that world.