I used the option 3 below, but what is not mentioned there is that is TDC for the tip seal.  TDC for the combustion chamber is 60 degree from there on the rotor; or 120 degree on the eccentric shaft.  Easy enough to figure degrees by counting teeth on the starter ring gear.

Al G

 (3)

Or,

(Similar to above)

Take both plugs out of number one.

Turn engine in running direction until an apex seal appears in the trailing plug hole.

Gently turn the engine backwards until an apex seal appears in the leading plug hole.

Half way between those two events is TDC. With practice, accurate enough to do by just feel and rocking back and forth by hand and to find TDC within a few degrees, or close enough to drop in the distributor and have the engine fire instantly and run fine.