magnum's

I have been thinking about puting in a 360 magnum (? liter) motor in my demon, but dan't know when they started the magnum series? My thought on this is for the roller system in the motor. I have a 73' 340 that needs crank and full rebuild so I thought that the magnum's would be a better way to go and down the road I could put a stroker set-up in it. Opinions on options would be greatly appreciated. THANKS