The Type 1 and Type 4 camshafts are similar in design and layout. The Type 4 cam is slightly longer. Both of these camshafts are aftermarket cams and use bolt on cam gears. The Type 1 camshaft is an Engle W-100 and the Type 4 is a Scat C-25. They both about the same duration, though the C-25 has quite a bit more lift.

Here you can see the difference in the camshaft lobe. The Type 4 cam lobe is about 1/3 wider than the Type 4. The bearing journals are also larger on the Type 4.

Here's a close up of the end of the Scat C-25 camshaft. You can see the details of the camshaft here. The extra part on top of the camshaft(after the last bearing journal) is a lobe for the mechanical fuel pump.

The Type 4 uses 5 bolts to mount the camshaft to the cam gear. This particular cam gear is one I found in a junkyard engine. It's an earlier gear made out of a softer metal. I'm going to try it and see how it works.

Here's a side shot of the cam gear. Notice how the cam gear bolts protrude. This protrusion can lead to problems with the oil pump. Make sure to check that the bolts don't interfer with the oil pump.