Talk to Terry at CH..I got a Mc in a trade the had been worked on by them..
Kept the ignition and sold the motor...
To tell the truth, a Ryoby31 with a 18-6 woodie and a CH ignition is a real dependable and fun engine..
Whacker sells a great motor mount with all the goodies for about $18.00
Guage the reed stop to 1/8 inch and go with a bigger carb and weld a 1/2" peice of electrical conduit to the back of the stock muffler to open it up for flow and that should be good enough.

Their's no one around here that wants to work on a Mc if anything goes wrong..

Just my 2 cents...
BB1