Reface is a pig to block because some ingredients have been removed from it, try DuPont's polyester spray filler, it's better than reface and it costs the same so I am told.Upol fantastic filler finished with 180 grit, then two coats of upol reface. ( it's a bit of a pig to block sand 320 grit but it wont sink )
Then a good quality high build 2k primer again block sanded something around 500/600 grit then finish with
800. Leaves you with a good stable base on which to apply top coat.
That's how ive done it for over 20 years.