Re: Nutritional Pumpkin substitute
As Titchou says, there are other forms of squash (especially winter squash) which will give similar nutrition. They are normally purchased fresh, but they are easy to cook and store in the refrigerator for a few days or in the freezer for several months.
Another possibility is to look at sweet potato or yam. These are root vegetables with a higher starch content and thus a higher calorie content. They also have a high Beta Carotene (plant version of Vitamin A) content and lots of fiber. They cook up to a similar consistency as canned pumpkin, so can be used in similar recipes. You might be able to find some in canned form.
While you're waiting for the new crop of pumpkin to come in, you might want to consider that carrots can be cooked in lots of ways, including being grated into soups, stews, stir fries, etc. Carrots are high in fiber and Beta Carotene and low in calories.