T112 is the standard contemporary civilian ( and militarised civilian ) 1941-47 4x2 half ton truck engine. Pretty much the same as the T214 but it normally came with the three speed transmission, though it would take the four speed with some bellhousing tinkering. Engine accessories will interchange.
That engine bay is set up for a 23.5" engine ( they came in two 'lengths' measured at the head to block joint, 23.5" and 25" ). The problem is the block was designed originally in the early 1930's for a smaller capacity engine, in both bore and stroke, and by opening up the bore as they did, you end up with two cylinder pairs that are very close together. It is always the head gasket bits between these two close pairs that causes problems, since it is little more than 1/4" wide. If the rest of it is fine, get one cylinder sleeved then the block decked.
If you can find a spare one you can fit a T214, T215, T211, or T207 engine, but if your Clarktor has only three forward speeds you'll have to tinker with bellhousing, clutch, and so on. Sleeving a single bore much easier. If it is sleeved you should be fine, but if you are worried just click the radiator cap back part of a turn and run it unpressurised. The maximum radiator cap pressure on these engines was 4 psi. If you replace the cap with a higher pressure cap - bad things happen. Speak to Steve Rivers at Dallas Autos about bits, but be sure to mention T112.