With the grain of sand blasting I begin with dry 240 then 400 dry again and go with 600, 800,... wet. With this work no need to go to bodybuilding room.... For sure, the powder paint of the front triangle will be very dry before I finish the rear...Can´t really give any tips regarding polishishing besides the obvious: Start with 800 and work your way up to finer grit. I usually stop at 1500 and change to 3M pads, then your choice of polishing compound. Maybe use a certain multitool (can´t think of the name right now ) for the welds? Hope your elbows are well greased ...