350 Serpentine belt conversion and intake gasket

[t5noel]

I know there are a ton of threads concerning serpentine belt conversion and I searched it all before I opened a new thread.

While reading up on installing 350 intake gaskets I found out that the gaskets on engines with a reverse water pump (serpentine setups) had the two rear water ports blocked. I am in the process of putting a new 350 in my 74 GMC truck with a serpentine system. The 74 350 did not have the rear ports blocked. Should I buy the intake gaskets with the rear ports blocked? Is it an issue at all?

I also noticed while digging around that the 99 Suburban with a 350 did not have the rear ports blocked. I might also add that I'm putting an aluminum intake on it.

There has to be someone out there a lot smarter than me that can explain this.