How to know what modifications have been done to 318?

I'm a new Mopar owner, I just bought 1975 Scamp with a 318 2 barrel carter with headers. It runs pretty strong just on a 2 barrel and no vacuum leaks, but has a good lobe to it at idle. How can I know what has been done to motor with no history from previous owner? My questions are:

1) I how it has been camed, but how to get specs? I know it is going to need to be torn down to measure. Do you measure the height of the lobes to get the specs? Standard specs?

2) How do I know if the cylinders has been bored out? Again, I assume a with a measurement across the cylinders. What is standard?

3) If any head work has been done?

Thanks for your input! I am just trying to put this puzzle together for a new intake and carb. Thinking about the Edelbrock Performer 2176 intake and the Edelbrock 1406 carb. I want to make sure this is my best option. I have also read 360 heads are better, but if the heads i have now have been done, is there any reason to go that route?

I'm just looking for a good streetible motor, that will accent the mods that have been done already! I'm not looking for a drag car nor a lot of HP!

Thanks again for any input!