I ran a DSS/SVO MSS on my stock block 306, got it for sale if you're interested.
The instructions recommend that you align hone the main journals after you install the MSS and ARP studs... if you already use studs, I'm not sure this is necessary. However, I do know that when you change from main bolts to studs, it is highly recommended that you have the main journals checked for proper runout.
Other than that, when I installed mine I had to clearance the girdle to clear the 7/16" rod bolts on my C&A rods (3.00" stroke, 5.400" rods), had to modify the moroso oil pickup to conform to the shape of the girdle (a tool is included for re-profiling the oil pickup tube), and relocate/reweld the mounting tab that retains the p/u to one of the studs. I doubt you'll have any clearance issues with stock rods/bolts, but you will have to reshape the oil p/u tube.
I picked the aluminum support over the steel version for what was described by Eric, in that it absorbs engine harmonics, unlike the steel versions...