I recently did this when installing a motor in a friends truck. I found it to be easier to get a hole saw the size of the pcv valve grommet or just a little smaller and drill out whichever valve cover you want to use. as far as the baffles I would ust some red loctite to put the screws in and help them stay put. You might have to use a file or die grinder to finish sixing the hole to fit the grommet. I alsmost forget before you start to drilling check the depth of your pcv valve grommet. I had to had to use a little bigger hole saw to thin out the mounting flange on the inside before i drilled my final hole.