You have 2 options:

Remove the original water modine (the thing with 2 water pipes going into it) and put the sandwhich plate in it's place. You will also have to rework the water pipes so basically the hose that comes out of the head near the dipstick goes straight into the heater matrix on the exhaust side bulkhead.

or

use a remote oil filter.

The 1st is the easiest option