If I take enough Vyvanse (lisdexamfetamine) will it keep me awake to do my work, without overdosing?

Not a great idea. The use of stimulants for staying up for long periods of time is longstanding. It can be effective in the short run; but, depending on how long you need to stay up, you may end up requiring quite high doses, which increases the risk of side effects. Moreover, people need sleep: it's good for you. Also, not clear that information crammed in while on stimulants is readily available later.