Commercial 3 Phase Question

I don't even know enough to be dangerous, so forgive the rather vague question..... We have leased a commercial space and we are planning the build out that needs to occur prior to getting the sub contractor quotes. We want to have a rough idea of what is practical before the quote stage. We are creating an area within the space that is going to be a kitchen area and will need all new circuits run for it. The main 600 AMP panel is quite a distance from where this needs to occur. Across the roof is (what was referred to by the owner as a 'bus'). It appears to have been a three phase supply with a series of boxes that machines were individually attached too with power drops. Is it possible to tap into this supply, convert it to single phase and power a sub panel from it? This would mean we wouldn't have to run significant amounts of wire to get power where we need it. I am assuming that IF it is possible, this would be a cheaper solution that wirig a supply line all the way to the sub panel location? I know this is vague, but generally speaking does it make sense? Thanks for humoring me!