Brake Booster question

[72LSLB]

I'm going to purchase a new booster/master cylinder setup for my 72 C10 pickup for more clearance to my 4.8 LS and to clean up the engine compartment a bit. I'm going to buy this one https://www.performanceonline.com/19...ster-Cylinder/

What I need to know is they have a 9 inch single and an 8 inch dual booster as choices. Is there a benefit of one over the other and do they mount the same way? An 8" will give me more clearance so that's probably the path that I take but just wanted to understand the ins and outs of a single vs a dual booster.

Thanks