Collaboration Beer

My brother and I are doing a 10 gallon collaboration beer. Each of us is brewing 10 gallons, then taking 5 gallons of each and blending them. He suggested a pumpkin ale (which I've not done before). I suggested that we make it an Imperial weighing in about 8%. The idea is that we each do separate beers and combine them for a third version. He will be doing a pretty straight forward ale using WLP001. I was thinking of doing an English version using WLP007 and Lactose. Does anyone have a suggestion for an Imperial Pumpkin Cream Ale? I'm thinking of using the following:

20 lbs Pale Ale Malt, Northwestern (Great Western) (3.0 SRM) Grain 3 77.7 %
2 lbs Extra Special (Briess) (130.0 SRM) Grain 4 7.8 %
2 lbs Oats, Flaked (1.0 SRM) Grain 5 7.8 %
1.00 oz Goldings, East Kent [7.20 %] - First Wort 60.0 min Hop 6 12.6 IBUs
1 lbs Milk Sugar (Lactose) (0.0 SRM) Sugar 7 3.9 %
87.00 oz Pumpkin - 100% Puree (Boil 60.0 mins) Other 8 -
2.00 Items Whirlfloc Tablet (Boil 15.0 mins) Fining 9 -
1.00 oz Goldings, East Kent [7.20 %] - Boil 15.0 min Hop 10 5.7 IBUs
5.00 tsp Pumpkin Pie Spice (Boil 10.0 mins) Spice 11 -
12.0 oz Molasses [Boil for 10 min](80.0 SRM) Sugar 12 2.9 %
1.00 tsp Vanilla Extract (Boil 0.0 mins) Flavor 13 -
1.0 pkg Dry English Ale (White Labs #WLP007) [35.49 ml] Yeast 14 -
2.00 tsp Yeast Nutrient (Primary 3.0 days)