You're going about this backwards, you cannot succeed in the food business basing on other folks menu prices. You will go broke doing that.
1. Set what you are going to serve. Be complete in this, account for all the food on the plate, from main to sides and condiments.
2. Make an estimate of how much food you expect to sell each day, break it down to the point you know all of the components.
3. Find out where you will be buying the foods.
4. Build a detailed shopping list and find out your hard food costs. From there, you can figure out how much each menu item costs you to produce, include fuel, charcoal, wood, spices, your time. From there, figure out how much you can charge using the rule of 3x or 4x food costs. That will tell you what your profit is. From there, you split profit, not gross.
5. Beware, and I mean, do not enter into, any agreement that has you splitting off a share of your gross. Even a 10% share of gross really can mean you make no money. Do your leg work, estimate profit and let him know what you will share of profit.
I'm feeling bearish, and I'm packing a Wusthof Grand Brisket slicer from MABA
"perhaps...but then again...maybe not..."