Regarding meter capacity. I ~think~ (from my terrible memory) my downstairs furnace was 100K BTU, upstairs furnace 50K BTU, HWH 40K BTU, stove/oven 50K BTU (every burner and over running same time)...
I had researched my meter online and found markings on it that indicated it was enough for the house, but not enough for the house PLUS the generator if an outage was during a cold weather period.
I'm on a rural "mom-and-pop" gas company... Called central office to verify my meter's BTU rating.... I think it was 225K or 275K BTU. Barely adequate for the house alone.
Lady at the office (an actual human) gave me the cell number of "one of her guys"..... Within 25 minutes, a pickup truck shows up at my house. He has a meter in the PU bed... 15 minutes later he was done. He swapped out my meter for one capable of 450K-475K BTU.
Another consideration is size of natural gas line leading to the generator - all the way back to the meter; and the regulator on your home. A plumber can help you calculate these based upon your own situation and the chose generator's specifications.