Too much heavy cream in my pumpkin pie?
To understand the Food.com recipe you referenced, I compared it to the Libby's recipe which sets the benchmark for pumpkin pies.

              Food.com     Libby's

Raw measurements

Pumpkin       6 c          2 c
Sugar         2 c          0.75 c
Eggs          8            2
Dairy         4.5 c        1.5 c

Pseudo-bakers percentages (eggs as ratio of cups pumpkin to eggs)

Pumpkin       100%         100%
Sugar         33%          38%
Eggs          1 : 1.33     1 : 1
Dairy         75%          75%


As you can see, other than creating a huge volume of filling per shell, the Food.com recipe you used is quite similar.  The main difference is that it adds a lot more egg, so should set up more firmly.

It does seem to produce far, far too much filling for the number of shells specified, even if they are deep-dish.

I would suggest baking the extra filling in ramekins or baking dishes as pumpkin custard for any surplus after you have filled your shells.

Don't add more ingredients to the filling, though; they are approximately balanced already.  Remember, pumpkin pie is a custard, and the filling will be quite liquid before it is baked.