273 Commando Air Cleaners and Valve Covers

I found a used Fram CA160 filter laying in the trash and tried it in my slant six lid. (I think it was a CA160... came from a '67 Polara with a 318). It seems to fit the registers good. there's around 1/4 inch clearance all the way around... kinda tight, no? If that's the same as a 273 4bbl, then that means the lids should be the same then (there are two locating grooves on the lid... an inner one for the TINY slant six filter... and an outer one about 3/4 inch or so out from the inner one). Anyhow, trying it on a thermoquad, it's going to be tight... can't really fit a drop base with a filter that small. But the TQ needs a base with a hole 5 1/8 inches in diameter.