2002 mobius LSV Carb, went to set / adjust base timing, but the crank pulley only has one mark instead of several (indicating TDC, -10TDC, -20TDC, etc.) the engine should be set to 10 degrees under TDC, but i cant really get to that?

I set the timing by just aligning the mark i had (while shunted), and the engine runs great on the trailer, but worried it's still not set right.

Anyone else see this, where thes only one mark on the pulley?