If I recall correctly, the MDS cams for the 6.4 use slightly different lobes on the MDS cylinders hence the different part numbers.
If your friend wants to keep the MDS function, get the MDS cam. Makes the swap a lot simpler.
If he does not want to use the MDS, he will need to replace the mds lifters with non-mds ones and have mds turned off in the ECM. This may require head bolts and head gaskets along with lifters and non-MDS lifter yokes(retainers.
If it was me, I would just use the MDS version and be done with it. Either way, the ECM will need to be tuned. IT is suggested that the Comp Cams Phaser Limiter be used as well. But people have not used it and had no problems with Piston to valve clearance.
In all reality that cam swap is only worth about 30-50hp at the crank depending on who you believe. And you may not even see that kind of gain with stock exhaust.
Hope this helps.