Hello Ken,
Your uniflow suggestion, together with a slight kick out at the rear, provided a trouble free system with a clear cut off at the end of the run.
As an aside I looked at a C/L Big Mig 0.061. The venturi diameter was huge compared to the Cox 0.049 venturi used on the Wasp. As the engines are very comparable design wise, is the Big Mig venturi too large or the Cox venturi too small? A bit academic as both engines run well with plenty of power to spare. It is just that the disparity in throat diameter is so big.
Regards,
Andrew.