What pan is it? Not any old pan will work with a jet drive.You need a jetboat oil pan.
Im sure you know this, but the hot ticket for a jet drive pan is the Dan Olsen full kickout pan.. I believe its a 14 quart.
I saw the merlin block you bought, good choice. I bought some parts that were on that engine too. Remeber, when you do this build up, its alll the little things that end up making good power, try and find a good pan if you can.