I have a recipe for squash cassarole that calls for 2/3 cup of evaporated milk, but I only have whole milk. Can this be an even exchange?

I think half heavy cream and half whole milk is a better substitute, but it should be OK.

FYI: Substitute Evaporated Milk for Whole Milk

HC's reply says it all
What I do is use the evaporated milk and keep checking it. If it looks like it is getting too thick stir in a little water.