I think you may well have better luck with 1hr 45. As always there may be some disruption for a few days with the change, he could well wake early OT for a day or two but then settle into the longer time.
If his morning WU time does become later again remember you will need to move the nap a bit later too so that the A time doesn't end up short again, so timing from when he wakes.
4 months is about the time to move to 4hrly feeds but if you feel he would do better on longer E times then go for it, it's not a hard rule, some LOs are put on longer feed times from birth if they have to stay in hospital, meanwhile others can't make it more than 3hrs until they are 6 months old (mine for example). It's ok to have EASAEAS rather than EASEAS, just try not to feed too close to a nap time so that you don't start a feed to sleep habit.