first off sorry for being long winded but it may save a lot of ?'s back and forth. my experience with s.s. is limited but maybe insightful. first are the pipes are new? or scratched up?, i assume not brand new as you intend to sand them or is this just because of the mill finish?. second the lathe is a good idea in that the speed selection is broad. find a wheel that you are comfortable with that will not allow the pipe to contact the spinning chuck. as for compound if the pipes are new then all you should need is the green and white. if they are scratched then start with black i recommend the vented wheel as i am haveing great luck with them. if this is still not as good a shine as you want then move from white to red then blue. make sure to coat with some sort of polish till time to install so fingerprints dont discolor the great finish you put on those bad boys
. please post pics if possible so we can all see. also there are some on this forum that may dispute my recommendations and rightfully so as i said my s.s. exp. is limited.