How do you know your P30 is any good? This might be a good time fo find out.
If you are determined not to waste a drop of it you could poke around for some P3 bleach, which was available seperately, and make your own developer and use rapid fix. But that seems like a lot of effort to go to when you have some P30 chems right there. If either the chems or paper are no good, it will save you greater disappointment to find out sooner rather than later.
How old is the paper and how was it stored? Knowing that might alleviate the need for testing. If its much more than 10 years old, or stored more than 2 years at room temperature, its probably a lost cause.
You could also look for some stand alone P3 bleach lying around some corner of the internet and mix your own developer and use rapid fix. But you'd still be gambling that the bleach is good. I don't know what life expectancy of the concentrate is.
The chemistry is ok. A few month ago I try to develop one sheet of paper and the frame was blue instead black:-( I lost 2 liter of chemistry. I received from my friend one pack of paper (30x40). And I afraid to lose next set of chemistry (If paper will be "damage" I would like to give someone this chemistry who have good conditions paper, in freezer)
The dye bleach and the fixer may last quite long, even as used working solution. Slight deviations may not matter much if you use aged paper and have to adjust your process anyway. If the first developer goes bad, you can use any B&W paper developer instead, I used a self mixed Dr. Beer's developer interchangeably with Ilford's.