Replacing speakers in G-Flex

I just got the 50 watt 5153 recently and I am using a G-Flex 2/12 with it. Been debating wether to get the matching 5153 2/12 or replace speakers in the G-Flex. Anyway, the 5153 cab has the celestion 30 watt Heritage speakers in it. I am wanting to put in the Reaper 55hz in my G-Flex and would like to know if these speakers might be compatible with the ported cab, or if anyone has actually tried this combination yet? Thanks!