Can I run a disc image of a cloned Tiger or Leopard PPC drive on a modern Intel Mac via virtualization software?
Mac OS X SLA doesn't allow to run older Mac OS Xs in a VM until Max OS X Server 10.6.8 or Mac OS X 10.7 and later. Additionally there are some technical restrictions.

So none of them will run directly in VMware Fusion, Parallels or VirtualBox.

To get an image of the MacBook3,1 running in one of those three you would have to update it to Snow Leopard Server 10.6.8 or Lion 10.7.x first. The easier and cheaper way is probably to set up a vanilla Lion VM and migrate the content of the MacBook.

The only way to get the PowerMac G5 possibly running I know of is outlined in this guide. You would have to migrate the contents of the PowerMac as well.
Probably it's easier to choose the simple way and use the same approach as with the MacBook: vanilla Lion VM and migration.