Heavier tail will make it more maneuverable. Heavier head will give power.
And spin is the result of your swing path and has nothing to do with a racket's balance. I mean, IF a particular racket's balance doesn't feel right to you, any stroke will go wrong.
So, don't go by "formula". Customize it such that it's right for you.
PK REDONDO TALKS & INTERESTING LINKS REGARDING REDONDO:
Making a Super Redondo:
"Don't play what's there. Play what's not there." -- Miles Davis