The Gospel for the Ascension shows the following quasi-chronological development, according to Beissel:
- Greek: Luke 24:36
- Gallican: John 13:33, Luke 24:49
- Spanish: Luke 24:36
- Mozarabic: John 16:15
- Ambrosian: Luke 24:36
- Celtic: Luke 24:44
- Carolingian: Mark 16:14
Luke 24 is obviously the older but is supplanted by Mark 16 in the Sarum and Tridentine rite (where Mark 16:14-20 is joined with the Epistle Acts 1:1-11). This is how it appears in the Book of Common Prayer -- until 1928, when the Gospel reverts to Luke 24:49. (But there is no need to pursue the most ancient simply for the sake of primitiveness.)
The Introit is Viri Galilaei, quid admiramini auspicentes in coelum? and the Collect is rendered admirably as
GRANT, we beseech thee, Almighty God, that like as we do believe thy only-begotten Son our Lord Jesus Christ to have ascended into the heavens; so we may also in heart and mind thither ascend, and with him continually dwell, who liveth and reigneth with thee and the Holy Ghost, one God, world without end. Amen.
The most minor restoration would be to simply supplement those (received) readings with a Prophecy -- as in the Mozarabic, say, with 2 Kings 2:1-15. Why prefer the RCL "solution"?