Rebuilding a 65 273..I need some help.

Very good info. It seems the heads I have are good ones. But would I not be better served just buying a set of 302 castings and prepping them and just doing a head swap? they already have the hardened seats. Are they La heads or magnum heads?
Let's get back to what you are trying to achieve here. Just a little more power? Might as well stay where you are with all the bolt on's you have already. A slight cam change won't get you much more and at what cost? The next step up with a size-ably bigger cam that will make a difference will require higher compression and more cylinder head. Now, You are already at +.060 over right? Unless you are able to kist scuff hone the block and replace the pistons for some high compression ones you are on a sinking ship. You are already maxed out. Oh you could have the block sonic checked and bored again with custom built pistons. $$$$ Or you could have the block sleeved to bring it back to standard. (also $$) See where I am going here? You can put in a slightly bigger cam (like I mentioned, don't go too big) and be happy with the performance. Simply put, you are at the point, unless you go all out, nothing you do is going to make a lot of difference from where you are now. That's my take.