Rear speakers 1980 buick century noob

[a1980century]

I just came into a 1980 Buick Century that got passed around through family members (no one wanted it!?) that just barely has 23,000 original miles. I bought a Pioneer deck and a set of Infinity Kappas 3.5" fronts and 5.25" rear. I didn't want to go oval in the rear and now that I have the speakers it looks like my plan of getting them in the rear deck might be a tight fit.. Has anyone ever put speakers in the rear pillar? I'm guessing I would need spacers but if any one has pics or info it would be appreciated.
I was thinking that would leave the 4x10" holes open for when I get my subs.

Also, I know there are screws on the dash cover up front, but if anyone has a pic or can give me tips on removing it without it breaking or breaking off tabs I'd be appreciative.