Pixel height and pixel width is all there is to resolution in an image file. PPI, DPI, centimeters and inches are just metadata there to help you calculate print sizes.
That being said most people producing exhibitions and printing magazines don’t understand this, so you’re probably best off complying by setting PPI to 72. 
If you’re sending JPEGs and they already have the right pixel dimensions this should just edit the metadata (JFIF:XResolution if tag exists, Photoshop:XResolution if tag exists, XMP-tiff:XResolution if tag exists and IFD0:XResolution):
exiftool input.jpg -xresolution=72 -resolutionunit=inches -v2