I was already thinking of doing that. I've done it on truck wheel arches, with good results. On the outside, I used the West Marine 410 fairing filler. Thanks for the encouragement!
I guess while I'm at it, I can cut off that port on the air cleaner base and seal it up. Is it intended to provide clean air to the crankcase? I assume it was capped when installed on the original car, which would explain why it's so rusty.
Wow, I had it all wrong (not the first or last time!). The smaller port in the throttle body is clearly intended for the heated air inlet system. It leads directly to the groove in the base, same as the one in the manual but shifted over to make room for the 2nd large port. I assume the 2 large ports are to give you a choice of PCV routing direction.
