So you want to put "oil" or what ever is in your catch can back in the crankcase?
Please tell me what a piece of screen is going to do to remove methanol, water, acid or what ever other crap ends up in your catch can.
If it was me i would fix the real problem.
I'd figure out why i was getting all this liquid in the catch can.
Some reasons could be but not limited to:
Bad seal.
Worn crank
Loose bearings
Loose piston
Loose rings
Fat carb
You are putting too much oil in the engine to begin with
Wrong plumbing (i see this all the time, even on engines from other "engine builders"
I recently had a big block open that was pushing oil out the FW side seal.
This engine originally had a factory bushing rather rather than a ball bearing on the FW side.
I tried 2 new seals with out success.
I tried a new bushing with out success.
A new crank probably would have fixed it.
This crank was worn very slightly on the FW side but it had so much other work done to it previously that i didn't want to spend the customers money on a new crank and go through all the modifications and spend more of his money.
What i did:
I machined the crank down a couple of thousands to get it perfectly round again and made a new bushing for the block with the correct clearance.
I was really surprised that .001" difference in clearance solved the problem.
I have had other engines with more clearance than this one had but didn't have an oil leakage problem.
Live and learn.
"Life is like a box of chocolates" Tom hanks
I'd suggest you take all those hoses ( that i think you have) off the side cover that pump copious amounts of oil into your catch can and install this:
You can choose from the Briggs version or mine.
http://www.fastermotors.net/Breathersystem.html
Oh yea, if you took the baffle out of the valve cover put it back in.