I can see 2 possible solutions:

1) Dig into your problems with these gems and either fix or replace them 2) Think again if you really need Rails 3. What are some benefits that you will get from that upgrade?

I'd suggest 2 approach. Rails 2.3 is a very solid version and is used in many apps. I don't see reason to "upgrade for upgrade". Especially if there is some friction and not enough time.

I recently made very small project on Rails 2 just because all I needed was ActiveScaffold(not available in Rails3 atm)- which is really awesome for some stuff btw.