You can place a button in your portal's row that performs a script with Go To Related Record to bring up the record from the clicked portal row for you layout. You can also group all your portal row's fields and make that your button so that the user simply clicks the row to pull up the record for the current layout.
Go To Related Records is a very useful tool, but which is very poorly documented. To learn more about GTRR, click the following link:
The Complete Go To Related Record
Thanks again PhilModJunk for your help.
I have not only got it working by grouping my portal fields, but I have also learned a lot from the link you added.