i think you cant completely disable all p-cores ,. atleast 1 p-core have to run,.
if we assume e-core (like i5 6400 , 4 cores)
8 e cores give- single 902/ multi 6460 cbr23 score
4 p cores give- single 1722/ multi 7540 cbr23 score
1 e core give -multi 807 score ; 1 p core give - multi 1885 score;
like 1p core =2.3 e cores,.
in total,.
12cores give- single 1722/ multi 14000 cbr23 score.
(note , all values are just assumptions ,..not tested) ,. in my 13th gen cpu , 1p core =2.5 to 3 e cores,.