[Philliphastings]

Alex, if you stumble across a flathead engine with the flat bottom pattern sump fitted then chances are you've got yourself a carrier engine. Also you should look for the extra oil gallery fitting on the left rear upper flywheel housing (standard engines have pressure out fitting only - carrier engines had extra fitting for oil return to the gallery from the carrier oil cooler)

It is pretty important to try to find a block with this extra fitting - carriers tend to run fairly warm even on a cool day. While it is possible to drill and tap the extra fitting into a standard block, it is a pain in the #ss to have done.

Also with a non flat bottomed sump the engine won't clear the hull floir and mate up to the carrier engine mounts.

good luck

Phill