Dave,
When you say it likes to run backward is running at full rpm or just half running? If it is running at full rpm then it might have a reverse crankshaft that would allow it to run clockwise. Fox made this type of crank for the 35 & 29 (I have one). Look down the venture and see what side opens as it come up on compression. If you have a reverse crank use a pusher prop (Zinger make wood one). Let us know what you find.

Best,    DennisT

I bet it's flooding.  Instead of choking try priming in the exhaust port.

I was gonna say the same thing Russ said. Too wet on start up. Also, in my limited experience, the 29 likes a 9 inch prop.
I choke flip mine 3 times and clear it out with 6 flips. Hook up the battery and one sharp back flip.