I don't know of any depth clearance issues with the '49-53 truck pan in a carrier, but the truck version of that year is the ideal version to replace earlier engines, as it has the "Feet" on the water pumps and as you noted, it has the adapter ring to mount up to the 4 speed truck gearboxes. The '49-53 Mercury car also had an adapter bellhousing made of stamped steel, but this will only clear a 9 1/2" clutch, while the cast adapter found on trucks will clear an 11" clutch (as found on Carriers and CMPs).
I think the only clearance issue you will find with the truck pan is that the oil drain plug might not line up with the plate on the bottom of the carrier's hull, making oil changes messy. Does your pan have a small drain bung in the middle of a large (6" dia app) plate bolted on to the bottom of the pan? This was fitted to some truck motors to remove and clean the oil pick-up screen on the oil pump without removing the whole sump. If your drain plug doesn't line up with your hull opening, there are always a variety of '49-53 car style pans on
E-bay. If you were to re-sell your truck pan with the bolt-on plate on E-bay, you'd find it much more sought after than the car-style!