That's actually a pretty good idea
I just refinished my blocks after finding out my model year grilles can be pulled out the front like your body style. So at first I started with foam board at the back for the top and bottom, but I had clearance issues on the bottom so I ended up using the clear duct tape from the back side on the bottom grille and foam board on the top grille. I'll be monitoring my coolant temps closely these next few weeks as Texas heat returns
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