1968 340 timing

Unless you have to pass emissions, throw the factory settings in the trash and find what the engine wants for ignition timing. Never had any mopar ever want less than 10* initial/idle timing. You will have to adjust the mechanical advance in the distributor to avoid getting out of bounds on total WOT timing.

The engine doesn't care which tower is number 1 as long as it's phased correctly. If you want the rotor pointing by the book, you may need to adjust the distributor/oil pump drive gear for that alignment. Not all distributors have the keyway and rotor aligned the same.

#1 is drivers side, US cars, front cylinder...