So good news, to anyone having this issue. I was able to update the TXT spf record, by creating a duplicate custom record. In about 10-15min the Mailgun SPF record was updated to match mine, and my custom one was removed! The step does a delayed automated updating. Now my only issue is getting the SPF record correct. Hope this helps anyone else looking for answers! (You dont need to remove the Mailgun MX records)