Nothing wrong with a 76 Nova, especially if it is part of the family. As long as you are needing to do an engine overhaul, you might consider going to an earlier cylinder head with a separate intake manifold. The integral head as on your Nova tend to crack and are tough to modify.
With the earlier head, you can go with a Offy intake and easily mount the carb you want. Add headers and a mild cam and you will be set to go.
I would not worry about spending the money on the rockers unless you really want to build a performance (and significantly more expensive) motor.
