what type of port is best>

If you are afraid that your heavier port will overwhelm the dish, just use less and replace the missing volume with water the first time around.

It's not that much anyhow just a half cup.

Best of luck.

Sauertea - if you have and like heavier port, maybe use it. I don't think it would overwhelm the dish.
On the other hand, all the spices might cover its distinctive flavor.
Absolutely your choice.
Please let us know which wine you eventually use and how it turns out.

Thanks. We drink a lot of Port, but mostly on the heavier side, so wasn’t sure if that would be too overpowering.

Neither Bonnie Stern's original nor menumaniac's adaptation specify what kind of port. Since the recipe only calls for a half cup, buy what you like and can afford, so you can enjoy drinking or cooking with the rest of the bottle.
I would avoid both tawny port, which is even sweeter than regular, and aged fine port, which has a range of prices from expensive on up.
Best bet is probably a red port in a medium price range.