I would bid 2S. If 3C now is invitational I would still not bid it with my not-so-good-looking-8count as my suit quality isn't that great. If I don't know if 3C is weak or invitational now I guess will depend on what 1S-3C means. If it is some form of major raise, then I guess you have to discuss what this sequence now means. I remember I used to play, after a forcing NT, if responder had 2 bids available to bid a suit, a lower bid is weak and a jump bid is invitational. For Eg. 1S-1NT; 2C- 2D/H are weak, with 3D/H being invitational. If responder does not have 2 bids available but 1 like, 1S-1NT; 2S-, I decided to drop the weak hands. Obviously it isn't that great, but it was something simple.