Opinions on a phenolic spacer in AZ

[Kalums]

Ok guys I've searched on the forum and a few others around the internet, there are a lot of conflicting opinions and very few actual facts I can find, "To phenolic spacer or not to phenolic spacer". I've got a 71 GMC K2500 with a 350/TH350, I've currently got an Edelbrock 1406 and square to spreadbore adapter to the original cast-iron manifold which is leaking from the front water jacket/passage. I'm planning on swapping to a Weiand 8004 aluminum manifold and a Holley 80555C carb. I live in Phoenix, AZ... Am I going to need a phenolic spacer? If I do... Do I use the wood/composite (it looks like brown plastic? With wood shavings inside *shrugs*) one that came with the Holley? Or? TIA