Did you forget that you need to cough up 6c to convert the oppies into heads?
Unless you're just planning to sell them on market once they're in the money.
In which case you would have been better off buying the equivalent number of heads at 3.4c today, and sell them at 6.6c+.
The only advantage you're getting from participating in the SPP is leverage in the form of oppies, but it's a hefty price to pay (i.e. forgoing a significant gain).