First off, always try for st. normals as they generally do more damage.
I’ve been working on perfecting one of dialupsucky’s combos and this has a solid damage output:
L, M, H, f.H, H Jodan, (wait until the character is over Ryu and their body is around the same height as his head), L, M, H, L Tatsu, (character should be on the corner side again after hit) M, H, f.H, M/H Tatsu, M/H Shoryuken cancel into Shinku. Does around 680k, but requires a corner.
If you want to maximize damage output, try experimenting with combos only using Hard attacks, (i.e., j. H, L. tatsu, st. H, f.H, H Jodan, st. H, f.H, S, (super jump), j.H, H Tatsu into Shinku. Since damage scaling severely affects Ryu’s damage output, the idea is to use as few mediums/lights as possible.
If your goal is meter, than incorporate as many hits as possible into your combo. How meter gain works in this game is that you gain meter equivalent to the base damage of each individual hit (i.e., if a L does 60k worth of damage raw, you’ll get 60k worth of meter regardless of what part of the combo you used it in).
Just remember that long combos doesn’t necessarily mean higher damage with Ryu, and that should be a good start off point.