The full installer for 10.14.1 and the RecoveryHDMeta.pkg both have 140.0.0.0.0.Hi,
I tested both the delta update AND a clean install by downloading it from my second MacPro still with high Sierra (it won't let you download it if you're running Mojave) and none of them offer to install 140.0.0.0.
I even downgraded my BootRom to pre-mojave build (89.something) and the full installer brought me back to 138.0.0.0.
Delta updates don't upgrade or have Mac Pro 5,1 firmware, only the full installer or the Recovery update.
You have to do one of these options to install 140.0.0.0.0:
- install 10.14.1 from scratch,
- download and open Mac App Store full installer for 10.14.1 (~6GB download),
- manually install with 10.14.1 RecoveryHDMetaDmg.pkg. Instructions in this post, use the current RecoveryHDMetaDmg.pkg (~450MB download).