West Des Moines
It seem that you have over a quarter of the set listed as a Rare or better. doesn't that make it kind of tough to make (using the standard for the example) 1 rare out of 15 cards not very easy since there are so many rares?
I guess you can just divide all your piles into the rarities and then pull the amount you need for each pack.
That's a little bit of the point as the rares should have a higher variance in the packs than the C's and UC's. That's typically how a TCG tends to work.
The idea I'm kicking around with is this. Create packs with 1-2 more cards than the number of players. Draft 3-4 packs and start with 10 starters and the cards you drafted for an enhanced start.