You can build a new "no cut" FAB that allows the filter (and upper mount plate) to be installed without having to cut the notch for the carb accelerator pump bulb.
By using Vans new FAB kit and adding an approximately 0.700" spacer between the bottom of the carb and the FAB top mount plate, the mount plate and filter will fit nicely and not require a cut out.
Did this mod on an O-320 with the old style FAB. There is a degree of difficulty in doing this on an RV-A that already has the lower cowl air inlet snorkel complete....but is can be done.
I purchased spacers from Airflow Performance and milled them as needed to achieve the right stand off from the upper mount plate to the carb accelerator pump bulb, the gap was about 0.030" once torqued up with the mount hardware. There was plenty of vertical and lateral space between the lower cowling and the FAB even after lowering the FAB 0.700".