Developing neighborhood retail/office

I have been working in residential development for awhile now and an acquaintance who is more or less retiring has a neighborhood commercial retail/office opportunity in a very desirable location who wants me to either buy him out of the deal and finish the project or include his land in the equity stack. The economics are favorable and It will be a fully entitled and permitted deal. I have never done a retail development but have worked for multifamily / residential developers for years now and have a pretty good idea of what needs to be completed. Anyone with experience here with retail/office have any takes on what would be the most advantageous way to move this forward? My ideal circumstance is to control the development and make a 5-6% developer fee and negotiate 20% equity in the project and basically put in my sweat equity to take it to fruition.