If a tax on revenue was used the outcome would be companies would try to increase profits but reduce revenue so high margin products would be the goal which would mean higher prices / fewer sales.

I think the solution should be market based. Whatever rate google US gets from google Ireland should be available to any company and google Ireland should be forced to sell any services/ip to any company who requests it at that rate.

Doing anything else means the cost of the IP google Ireland charges to google US is made up.