Following Dan Horton advice i decided to install a fiberfrax insulation covered with a stainless steel foil. Dan provides a full kit, however import duty, shipment cost make it impractical to acquire here in Europe.
I started with a mock up made of 1/8 thick foam purchased at the local store. I marked and cut following the firewall contour and the oil filter recess. After fitting and trimming the foam mock up i moved into cutting the fiberfrax.
Using the same method i cut the fiberfrax parts for the oil filter recess.
I also tested the scissors on the stainless steel and they work much better than the aluminum scissor i got. precise cuts and very precise on the trimming.