Johnnyrock-

I have the same set-up you do. Same marks on the flywheel and same Langdon HEI. Longbox is right. Use the steel ball on the flywheel for timing and get a timing light that allows you to dial-in the advance. My 235 seems to run best when the steel ball is smack on the bell-housing pointer (which I believe is 4-degrees BTDC). I tried 10 to 18-degrees as recommended by Langdon, but my engine did not run as well. My testing thus far has been at idle and slow speeds down the street. I'm not fully road legal yet.