Agree...It would have been revealed during that three year period that Paul spent with the Risen Jesus...Even yet in Acts 26 Paul was not teaching the gospel of Eph 2...
When did Paul pen Romans? I think it was within 3 years of Ephesians. I guess it depends when we see the start of the Church. Is it Acts 28? Or Acts 13 where Paul declares for the first time that he is going to the Gentiles like he did in Acts 28. I have to ask for the timeline because no one has put a stake in the ground where the Gospel or dispensation changed. Was the mystery revealed during the first prison years in Rome? I think this point is important because we would have to assume Paul established churches under one dispensation or gospel and others under another. Or did he plant these churches and then rewrite epistles superseding the previous?
"It is not expedient for me doubtless to glory. I will come to visionS and revelationS of the Lord."(2 Cor.12:1).
Paul did not receive a single revelation from the risen Christ, he received several revelations from Him. Which as he received, was given by him to believers and received from him.
"Wherefore I beseech you, be ye followers of me."(1 Cor. 4:16). We are to follow Paul as he followed Christ. WHY?
"Howbeit, for this cause I obtained mercy, that IN ME FIRST Jesus Christ might shew forth all longsuffering, for a PATTERN to them which should HEREAFTER believe on him to life everlasting." (1 TIm. 1:16). Paul is our pattern to follow. As he followed Christ's revelationS concerning the dispensation of the grace of God and all that that incurred.