Sanding Silmar 249 Resin Sanding

What grade should I start sanding with once it cured?. Right now we are using West system and we start with 120 grit and goes all the way to 1000 before we clear coat. Will it be alot easy sanding silmar 249 resin. Thanks guys for any help.

The stuff I did with 249 had a gel coat layer but I sanded with 220 and cleared it.