340 has no timing tab...

You don't have to change anything. Here's all you "need" to do. Find TDC with a piston stop. Choose "where" you want your timing tab. Obviously, a place where you can SEE IT. Now make your new marker out in the open in a place where you can see it and get a light on it. Then put a new mark on the balancer right where your new timing tab is. That's your new zero mark. You can then mark degree marks as needed.