Have no idea what shape or color you will get, but they are both C.pepo and will cross readily. They will not be any larger than a delicata.

I'm sort of hoping to get something similar to the sweet lightning variety. which would be a a mini-pumpkin with improved flavor and/or altered coloration.

They're planted within 3 feet of each other so I'm pretty confident they're going to cross naturally, but I have done some hand pollination to make sure.