Well, I can't speak to the blend itself -- cassia and orange should be good, and lavender and orange, I just don't know about cassia and lavender from experience!
But the amount of cassia seems safe at 0.5% of total oils. Your total blend comes out to 0.88 oz/ppo, which seems a little high to me, but the orange may justify that. Assuming you're doing CP -- are you using 5- or 10-fold orange to help the scent stick? Otherwise I'd recommend some sort of fixative base scent like patchouli, copaiba balsam, or, since you're using a lot of orange, litsea. Just a little bit (maybe not even enough to change the scent too noticeably) should help the longevity of the orange