Just say no to rustoleum. I’ve used tons of Spraymax. Brett already got you started on prep. Use the body filler/glaze of your choice. For wood stocks that get painted, I’ve used cheap 3m glaze putty carded on hard and thin to fill the pores.
SprayMax 2k Rapid Primer Filler #3680031
NAPA paint stores will fill a can for you. Expensive tho.
Check out
http://kustomcanz.com/home for some fun stuff and a very reasonable price. Get your spraymax 2k glamour clear on amazon. They sell a 4 pack for the best price. All 2k products will last multiple days if refrigerated after you pop the seal. So, you can lay down a primer coat, put it in the fridge- come back the next day and use it again after bringing it up to temp. Same with clear.
You’ll need more clear then you think because you’ll need to sand n buff the last coat instead of being able to flow coat. You’ll get 2 good coats out of each can.