How to convert cook time and temp from 9" round cake pans to standard cupcakes?
Since I don't know exactly your receipe, the receipe I convert time to time makes 22 cupcakes.  You line muffin pans with with paper liners, scoop the batter about 3/4 full in the cupcake cups, and if your receipe does not have crushed pineapple in the batter, I really suggest you add about 1/2 can of crushed pineapples, without the juice, into the batter when you are mixing the batter. This makes  the cupcakes super moist as well as the cake. Don't mix the batter too much.  Preheat oven to 400 degrees  and bake 10 minutes and then reduce oven to 350 degrees and cook 30 to 35 more minutes.  At the 25-30 minute point check one cupcake with a toothpick to see is comes out dry and if dry they are are ready, or if just a touch wet you need a few more minutes.  Remember that they still cook in the cupcake pan AND I ALWAYS USE THE BIG MUFFIN PAN.  If you choose to use the regular sized cupcake pans I feel you should check at 15-20 minutes with the toothpick test. If the cupcake is wet then cook 5-10 minutes more.  Remember, IF YOU LEAVE IN THE CUPCAKE PAN AFTER TAKING OUT OF THE OVEN, THEY ARE STILL COOKING, SO IF READY TAKE OUT FAST.  Also another tip I learned years ago, if you have empty cupcake holes, fill with a little water, I don't remember why, but in some way it helps your cupcakes.  Enjoy!