Mid 13's are easy to get, if your on a budget. You dont need expensive aluminum heads.
I run mid 13's with TFS intake/cast GT40 heads/stock cam, and all the little bolt-ons you can name.
If you do want aluminum, Id go with the TrickFlow Twisted Wedge heads and Stage 1 TrickFlow cam. Run you about $1150 for both.
You can get GT40 cast heads or windsor Jr. heads all day long for $400-500 all re-done, that will get you in the 13's.
