what kind of a starter? is it a hi torque one, or a tiny small block one? a big starter might be needed if you have a healthy motor, or an aftermarket mini starter. also, use the biggest cables you can get(or make).i like 00 gauge arc welding cable for battery cables. you'd be amazed what a difference cables can make. how big is the battery? i know i am repeating what others have said, but cover the basics. just taking off and re-connecting the battery cables can make a difference.
1971 Nova(looks like 69 camaro from underneath!)
355sb, vortec heads, HOT cam,T-10 tranny, 3.70 gears 16" IROC wheels