6.1 cam in a 5.7

There are way better cams out there for 5.7's. You don't need to plug the MDS solenoids, you can leave them there. They aren't gonna hurt anything if you leave them in. You also need new cradles for the 6.1 lifters, the 5.7 cradles won't fit on the 6.1 lifters.

You don't need aftermarket springs. If I remember correctly 6.1 springs can handle up to .575 of lift, or somewhere close to that. 6.1 springs are cheap.