Depends what you consider "perfect".on the subject, to lock in a perfectiv spread is a 1:32 right? cause you just need the random stat to be 31
For Inheritence, I would say that 31/M/M/M/M/M would be ideal. 31 HP gives you the largest selection of possible Hidden Powers, and all from the Male (usually Ditto) makes it easier to get flawless everything else in one egg (1 in 32*32*6).
Also, 1:32 implies 1 to 32, not 1 in 32. So 1:32 ratio would be a 1/33 chance.