I am putting in a 50A sub panel to run 40A cookstove,30A water heater,30A oven,30A dryer,7 20A circuits. Will this work on 6-3 with grd NM cable

If all of the amp ratings you are quoting are for 220 with exception to the 7 - 20a circuits. Your going to have system overload with so much going on.

What voltages are these units your quoting?

I am putting in a 50A sub panel to run 40A cookstove,30A water heater,30A oven,30A dryer,7 20A circuits. Will this work on 6-3 with grd NM cable
Do not expect to be able to use the cooktop and oven at the same time as doing dishes with hot water. Let alone drying clothes.

That is quite a LOT for only a 50A panel. WHY so much on that panel and why only 50A?

Try running this plan by your local electrical inspector.