What's your route before midboss Kurumi, anyway? If you're dying on the first half of stage 2, could that death be moved to stage 1 Orange instead? Or do you still have bombs remaining at Orange? In that case, it'd probably be better to avoid dying at all before midboss Kurumi (if you're planning on dying there, perhaps you could suicide as you defeat her, double KOs still give you the bullet cancel bonus).
And yes, there needs to be more information about the PC-98 games. I'm not even sure how accurate the factors that increase/decrease rank on the wiki are, considering the EoSD ones were incorrect for quite a while.
That reminds me, does anyone know what determines the amount of points you gain after each boss phase in LLS/MS? It doesn't seem to be directly linked to number of bullets (it is for the final phase and Ex-Alice, but you gain more than the amount displayed at the top), or to your current graze count like in EoSD.