I looked up my notes from Jeff Schewe at a "mini" Epson Print Academy workshop. For small prints (under 8 X 10) at high printer dpi (2880) he recommends between 360 and 480 ppi for the file resolution. I don't think the exact ppi matters as as much as it can for halftone (press) reproduction. If you resize your image without down-sampling and the ppi falls in that range... I wouldn't bother to resample at all.