Chris, there is a very simple fix for this. Put a "T" in the pump pulse line and port one tube to atmosphere. The oil will discharge overboard and the Walbro carb will still have PLENTY of pressure pulse to operate the diaphragm. Trust me on this Chris - it will work. My OS Gemini 160 twin works this way and it has only a fraction of the pulse your Valach 80 produces. If for ANY reason it doesn't haven't enough pressure just put a small restrictor orifice in the overboard dump line. But trust me, you wont need it.
@chrisdoingrc this engine is a great piece, i have one waiting to go into something, and yes the carb is in a fine position, leaves room below it for the muffler too,
