Yes vortecs outflow the vette heads. But you also need a special intake to use vortecs. As for not doing it half assed, your modding a 305... your off to a bad start as it is.
But beings that you wont take anyone's advise about leaving the 305 alone...
The springs on the vette heads would not work with your cam, they are for a roller cam. If you do want the heads, Ill set them up with your springs and seals and lap the valves, but your on your own installing them, I just dont have the time for that at the moment.