YUM! Do you think I could use a GF flour for this?

I use King Arthur Flour's "Measure for Measure" (available at Target, where it is reasonably priced), which works quite well for gluten-free baked goods, especially ones like this Vietnamese Coffee Cake. Make sure that you buy a gluten free blend that is designed for replacing the all-purpose flour one-to-one.

There are some "gluten free flours" that require additional ingredients found in the blends drbabs and I have mentioned. Make sure you don't buy one of those. ;o)

Definitely. I use Cup4Cup, and I would substitute an equal amount in weight of both flours in the recipe (315 grams).