How to select a 3 phase generator for 75kva of single phase load calculated

Not a wise idea to load a 3 phase generator with just a single phase load. Why not get a single phase genset?

Split the load into 3 phases and feed. Then measure load current with clamp-on ammeter and make adjustments till balancing occurs.

Sin, how do you propose to split a single phase load so it can be serviced by a three phase service?

Use three phase Y connection with 4 wires. 3 live + 1 neutral. Connect each live with neutral so you are essentially making each phase behave as single phase. Divide the load equally on these 3 phases. For example, I have a furnace with 12 heating elements. I have made a bank of 4 heating elements each and then put 1 bank across each phase.