Plum Preserves a la Joy

Today my mom and I put up 8 lbs of plums in the form of spicy plum chutney and Italian plum preserves. The chutney is good stuff, a little kick. The plum preserves, however, take the cake. And come to think of it, they'd be great ON cake! I used my ancient Joy of Cooking for the recipe which was so simple, I remember still. Here goes:

Plum Preserves a la vintage Joy
-equal parts Italian plums (we used 4lbs) and white sugar (I used only 3/4 the sugar)
- simmer until fruit is soft.
- Remove fruit and simmer syrup until it thickens to your liking. Put fruit back in.
- add a whole orange or two, chopped up small with peel (no seeds)
- add chopped up walnuts (I put in 1.5 cups or so)
- bring back to simmer and then do water bath canning method

I don't know about the safety of canning nuts in jam like that. I need to read up, but it sure tastes good and would probably last a month in thd fridge.