Catalina don’t have MP5,1 firmware, so no, you can’t.I have a MacPro5,1 running Catalina (10.15.3) with SilentKnight telling me my firmware is at 140.0.0.0.0.
Also I'm running dual X5690 @ 3.46GHz (SMC Version (system): 1.39f11).
Having read your note about 140 -> 144 that says this:
I'm currently in a situation where I can't really do the suggested path there for upgrade. Is there a method for updating to 144 directly while on Catalina?
Additionally, MRT is at 1.52 and I'm seeing I should be at 1.55, anything I should do about that while I'm at it?
I'm curious if "Install all updates" with SilentKnight could possibly resolve the issues as well....
MP5,1: What you have to do to upgrade to Mojave (BootROM upgrade instructions thread)
Please fully read this first post, you will probably find that you have one or more problems described into the various notes below. Mojave will only install if you have upgraded your BootROM to the current release and your Mac Pro have a Metal capable GPU*. If you are trying to install Mojave...
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