porter question

hi,

i want to brew edwort porter recipe and i dont have flaked barley.
would it make a big difference if i wont use it (or replace it with oatmeal)?

here is his recipe:

11# 2 Row
1# Chocolate Malt
1# Crystal 40
4 oz. Black Patent
1 oz. Roasted Barley
8 oz. Flaked Barley

Mash at 150 degrees for 60 minutes

Add 8 oz. of Malto Dextrin to boil at 20 minutes

Hops.

1 oz. Northern Brewer at 60 min.
0.5 oz Cascade at 60 min.

The flaked barley is mainly there for body and head retention. Either the MD or oatmeal would do the job; or both.

Add another ounce to ounce in a half of cascades.

thanks.
could pearl barley or oats replace the flaked barley ?