which block to use?

I'm building a 340 for my 68 Dart convertible. I have a block that will need bored 60 over because it is currently 40 over this block is a 1970. I have a set of x heads to put on it the only thing I need is a set of pistons. I also have a complete carb to pan 1973 340 might need freshened up, I will put the x heads on it. It ran when pulled I understand that the 73 engine is lower compression. My question is will a 60 over block run cool and be reliable? Or should I build the standard bored 73 engine. I going close to stock maybe a better cam but nothing to radical.



Thanks
Brian