Dave,

Might those holes in the 1954 frame be available for the necessary removable-crossmember for the Hydra-Matic option?

I'll check my Hydra-Matic and non Hydra-Hatic frames tomorrow (If I remember).

Yes, Chevrolet decided in 1954 that the mount was no longer needed (for non-H-M trucks) - the new rear engine frame crossmember was much stronger in 1954.
pages 49-50 for frame changes - for greater strength