I have a P31-2, so can't help you much with the measurements. But once you do have them, you may want to check this out:
https://www.leesailcovers.com/mainsail-pack-1/Till I got this 4 years ago, I probably used my main 10 times in 5 years (just too much hassle to travel from island to island in the North Channel). But the first year I installed this I used my main more than twice as much in that year than I did the previous 5

It's great, and inexpensive compared to Doyle and similar makes. And so easy to work with, especially when you get the sail ready for use, but don't use it...you just zip it up again!!!
Contact Becky as she does these and sail covers, so she may already have the measurements you seek.
OR, you can have my old Navy Blue sail cover from my boat it that color works for you. It's just sitting in the garage.