If i'm not mistaken, the stock head volume is 54cc on the 289 head. Most aftermarket aluminum heads are 60cc and higher. You could pick up a set of used Windsor Jr. cast iron heads for ~$500 and have them milled .030 to get you close to the chamber volume. If they are fitted with a 2.02" intake valve, you will have to worry about valve clearance with an agressive cam. I can't recall if they are available with a 1.90" intake valve. With the money left over, you can add an ignition and distributor.
FYI... I bought most of everything I have from ebay, recycler.com, corral.net, and the junk yard. Take your time, do some shopping, and save a ton.