360 magnumblock?

Well building a 360 block up but wondering if its worth trying to find a magnum block or Run with the 360 LA block and put on the add-ons on to it. It sounded like the magnum block was a better start but is it more of a headache? Like the Mechanical fuel pump part is fine To pull the LA Parts off it to make a spot for the Pump but! What is with extending the Cam? Is that a option to buy or do i have to have it fabricated everytime i wanna change the cam???