Blocking and bodywork

I am going to be putting the dart into epoxy, within the next week and I want to get all my supplies ready.

I am planning on using the following grits

80 grit for rough filler work
180 for finish filler work

Final bock before sealer: 400

What grit should I use for blocking the high build?

Also, anyone ever order from here? 80 Grit Stick It File Board Roll | Rich Tool Systems