It's a little late now but a great trick for using stripper is to gouge up the paint so the stripper gets under the layers and lifts it in less coats and effort. I use 80 grit on a grinder but try not to grind too deep. You don't want to get too many 80 grit scratches where you are only going to prime. 80 grit is fine if you are going to use bodyfiller. If you sand with anything coarser than 180 for final sanding prior to primer you can/will have sand scratches come back a later time. Once I'm dome with stripper I "wash" it with a red scuff pad and lacquer thinner. Lacquer thinner drys the stripper and washes it away prior to sanding the stripper. If you don't get rid of the stripper and go straight to sanding all you are doing is sanding striiper into the metal.
I would sand the rest of the top with 180 to bare metal and get all the seam sealer out of the gutter. I like to use a waffle strip disk for the gutter. It will conform to the gutter shape as it wears. Start and strip a little at a time and by the time you get to bare metal it will be in a "U" shape the same as the gutter.
Once the top is all in bare metal and body work is done you have several ways to tackle it.
1)You can use an epoxy primer
2)Use etching on bare metal followed by a 2K primer.
3)If the top is in excellent shape you could finish sanding with 320 and scuff with a red Scotchbrite, wash with prep solvent, tack, then spray etching sealer (or epoxy mixed as a sealer) and then paint. No sanding. If you choose this I would just apply bare metal primer to the gutter, let dry, sand and scuff with a red Scotchbrite. Use a 2 part self leveling seam sealer (3 tubes) let that dry and lightly scuff with a red scuff pad, then apply etching, sealer, and paint.
Does all that make sense?
