You shouldn't have any issues at all on an O-200. I'm running one (after the fuel pump, to protect a fuel flow sensor) on an O-320 in my RV-4.
No way would I run it after a Walbro, @ 40+ psi, but at 3-6 psi, it works fine. I'm mainly concerned about the Walbro sucking ~40 gph through it, & whether it could induce vapor lock on the pump input. Guess I'll have to set up a test rig, to measure pressure drop.