Practice on a set of junk heads first. You don't want to make the whole port size bigger. mainly just smooth out any lumps or casting flash. Use a set of intake and exhaust gaskets to mark the outline of the ports and only open them up no more then 1 1/2 " into the ports. Open every thing up too much and you actually lower the velocity of the a/f and will lose bottom end torque. Just like if you just got a new welder and didn't have any/much experience welding, you wouldn't weld up a roll cage as your first project. Porting kits are available on line that have the different grits and shape of sanding rolls . Practice, practice,practice. The first set of heads that I ported were on a Chevy with a 350. They looked good to me but after I installed them, the car had zero power! Too much removed and the car ran like a slug. Good thing it wasn't my car and it was a Chevy anyway.