The only problem I see is that PS fluid is oil based and brake fluid water soluble. I would get as much out of the reservoir that I could with a turkey baster. Then I would refill it with brake fluid and start bleeding it from the farthest wheel from the master cylinder which would be the RR wheel. Then when it shot out clean brake fluid I go to the next nearest wheel which would be the LR. Then do the front calipers. You may have to blow the pistons out of the bore and put in new seals.