Do you have 3 milk feeds right now? These should still stay - one at WU, one in the middle of the day and one before BT.
I am not familiar with the method you mentioned, but the idea of EASY is that A times effect directly the length of each nap so we are tweaking the A times to get a good nap.
There is no reason for him to be OT on a higher A time, which will be an age appropriate A time. Of course, the decision is yours so if you think another method will work better for him, by all means go for it.