There will be very little difference between the two engines, other than the fuel injection (and wear!). The D and K cams are very, very similar - 280 vs 277 degrees of duration or something very minor. Nothing you'd notice without a very accurate dyno if even then.

As already said, just leve the two engines alone and run the current engine until it begins to show problems, then swap them completely, and rebuild the other one in your leisure.

Remember that if you swap cams you should use the lifters that originally went with it - in their original position. Put them in numbered bags as you take them out. They break into the cam lobe and wear will be accelerated if you mix them around.