What belts are yall using?

I have a 74 duster 318 no power steering and no AC (right now) I have a dual belt alternator on the car but was only running one belt i assume. Crank pulley has 3 grooves, water pump has 1, alt has 2.

My question is what belts are yall using? Im assuming with this setup ill be running one belt all the way around untill I decide to put the AC compressor back in the mix.