>>4152252Take a photo of a grey gradient card under white light, adjust your curves so that your RGB values are equal from dark to light, save that as a preset. You can apply that to every photo then adjust your white balance as normal to account for the light in the scene.
Do note that this may not be "true" to the emulsion, for that you'd need to wet print the gradient, have it scanned by someone with a perfectly colour corrected digitisation process, then match your curves on your scanned gradient to the print gradient.
Also, you need a high cri light source to digitise film.
