Small block help

I am aware that Dodge has a small and a big block classification. I am wondering about parts swapping of the small blocks. I have a 318 and have installed a set of 360 headers. I am doing a piece at a time.. I was wondering what easy to find heads would be the best to go with, and before you guys start with the 340 stuff hold on. I am building a budget car. So I am wondering about the 318 and 360 heads and whats up with 383's anyway. Small block or big block. How can I tell what tranny I have. I've heard the 727 number thrown around. The diff area I'll figure out. I'm a nine inch fan.