yeah you want around a 11 inch block or so to do 90% of 1/4 then a small flexible block to do rest.
but use 80 grit until glaze coat, i would coat panel with reg filler block, then use glaze only to fill 80 grit scratches
what i do it get it perfect then spread glaze, and use spreader to take it all back off again, and all thats left it what is filling the 80 grit scratches as thats all i want the glaze to do, as the filler did exactely what it is named for.
then sand glaze with 180 by block to, just to feather it out, then 2-3 coats urethane primer, guide coat it (a flat black paint works, sprayed all over light colored primer) so you can block sand again with 320 and see any areas hand missed.
once blocked it can be either primed one coat and sanded with 600 wet then right on to base or you can seal it and go wet on wet into base, i would go with the re prime route and wet sand 600, much cleaner
jake