Berm, I did the same mods as you on my 12" oval and am getting ready to do the same to my 15". The SPFs might have a little more clearance, as I'm running a 2.5" filter and still had some clearance. There is another SPF owner running a stout BB that used an 1/8" end mill to cut the base. He then welded in 3/4" alum strip stock to drop it. Now runs a larger filter without any clearance issues and it looks great. I may do the same in good time, but for now just eliminating that 3/4" 'collar' and drilling clearance holes for the float adj. nuts. is a great mod and it actually looks cleaner, too.
For those considering this, Pep Boys sells a valve cover grommet set from Spectrum (Spectre?). It has two 1.25" grommets, one for use with a PCV valve and the other for a breather. Buy two and use the PCV grommets. Use a 1.25" hole saw and some cutting
oil. Measure three times and cut once.
-Dean