Dips & Chins % of 1RM question

I just started ABBH this week and tomorrow will be my day for Dips & Pullups. I know I’m supposed to use 60% of my 1RM for the sets of 10. However, I am not sure how much of my bodyweight should be taken into account when calculating these since technically I am not lifting my arms. Does anyone have a formula?

Oubigguy, please see the paper by J.P.Catanzaro,previous issues No 313. He reports for pullups/chins, 94% of bodyweight.