Dave,
There is a guy on facebook control line group that has very nice tongue mufflers for the McCoy 35, it bolts to the side of the exhaust stack, very nice. On the other hand, the Veco 19BB is more power than either the McCoy or Fox 35 and will pull the Ringmaster very strong. Just set the Veco in a solid rich 2cycle and use a 9 - 9.5x4 APC prop (you want around 13 - 14,000 rpm. Don't use the standard vent tank go with a uniflow. If you get the weight in around 34 oz. ish it will do the OTS pattern with no problem. Also, use a long tail horn to slow the controls, you only need about 18 ish degrees up/down. Balance 1 1/2" behind the leading edge. Good luck, keep us posted.
Best, DennisT