Err ok. So reducing skill count by 20%, Skill points by 16.7% (the same as your ratio), I am making that 17/21/25/29.
I wouldn't really recommend that. You have to keep the demands of the pyramid in mind.
Absolutely any reduction to the skill point total of Chest Deep characters will be a hit to the power of some characters. 30 skill points is exactly enough for 2 Superb skills. And since the revised skills are not twice as wide as the original ones, characters made with them will be Superb at fewer things.
Same goes for Feet In The Water with regard to Great skills.
It's not the end of the world, but...it's a reason to keep the old skill totals at those levels.
Plus, those numbers give ugly pyramids. 16/22/25/30 would be prettier. As would your suggestion of 20/20/25/30. 18/20/25/30 wouldn't be too ugly either.
Incidentally, 25 skills with a skill cap of Great makes for ugly pyramids. If you want to cut points somewhere, I suggest doing it at Up To Your Waist.
(All "ugliness" judgements are subjective, I'm afraid, but I expect that I'm not alone in my tastes.)