I have a new customer who's experimenting with Adwords and asked me to insert code into the order completed page to track their conversion rate.  I don't see a way to do that other than editing the PayPalPayment.ascx (Am I right here?) which would affect everyone running the store module.  Is there another way to do this I'm not seeing that wouldn't impact the other sites?

Also, I've had several orders not switch status to paid, but the store administrator did get the email from paypal, is there a place I should be looking for the problem?

Thanks for confirming my suspicions.  If you were to theorize about the right way to address this so it could be incorporated into the core, (perhaps by changing this page to use a per-portal template)  what would that be?

This customer is going to be quite active and vocal, so I will probably end up making code changes, but I'd prefer it be done in a way that could be contributed back.

Basically, you insert a bit of javascript code in the page the customer sees after they have completed their order to track conversions from your adwords campaigns.  In the current design you can't have a different google_conversion_id for each instance of the store, so I was thinking that it might be possible to make a code change to allow this page to use a per-store template where this could be inserted into the template.