Mitch, CH and MMM used very similar intake manifold designs for their gas conversions i.e. straight up carb mounting, no 90° turn. May be the route to take if your design doesn't pan out as expected.
As far as recirculating crankcase oil? Saitos and OS 4 strokes are both known to run hundreds of hours running methanol or gas with proper maintenance, without recirculating oil. There are plenty of folks recirculating oil running methanol with no apparent I'll effects. There is one guy who has run hundreds of flights on gas while recirculating oil through the velocity stack. With only those examples to go by I lean towards the belief that oil recirculation is probably ok but personally I wouldn't begin recirculation until the engine was fully broke in. Just my thoughts.
Last edited by Glowgeek; 03-22-2023 at 05:26 AM.