"Triple C's" are a horrible way to take DXM. They contain CPM, which is an antihistamine and can cause horrible reactions at higher dosages.
If you had a bad reaction at 8 Coricidin pills (240mg DXM), then I wouldn't recommend taking 450mg your next time. We can't tell you if you're going to "overdose" because that's a very vague term, and you're technically "overdosing" every time you take higher than a medical dose.
Don't take Coricidin to get recreational effects from the DXM, it is not worth it. Some good friends of mine caused themselves brain damage from taking large amounts of Coricidin pills over an extended period of time. It is not worth it.
If you had blue hands and high blood pressure off that dosage, I would reconsider before jumping right in at 450mg. DXM isn't very fun to begin with if you ask me (although some people would disagree), but 450mg isn't where you should start with your dosing.
Again, if you had a bad reaction with a lower dosage of DXM, I wouldn't take a higher dosage next time.
I'm going to change the title of your thread for easier searching.