Can you see if there has been any work done to my heads?

krazykuda said
You have a good intake for that engine. Definitely keep it.

You cannot put larger valves in the 273 without having to notch the bores.

However, you can improve the flow with those heads with some good porting in the bowls and blending it into the gasket matched ports.

Then if desired, gasket match port the intake manifold and blend it into the intake ports.

Also, it is not good to mill a closed chamber head. With the smaller combustion chambers you will not gain as much benefit as milling an open chamber head. The closed chamber head also does not have that much volume that it can afford to loose before "washing out" the chambers. They have issues with "wash out" on open chamber heads where the combustion chamber was milled to far down and it looked like a closed chamber. Those were not allowed to be used. There's much less risk in milling an open chamber head than a closed chamber.

You can run 1.88 intakes and 1.60 Exhaust valves in a 273 without bore notches. You are getting close so you better check and give yourself some clearance. It also depends on valve lift.

Although I can not be sure from the pictures, I appears that his heads are gasket matched. I'd also bet they are at least pocket ported.

There are no problems milling closed chambered heads small or big block. What do you mean by "wash out" ?

From what I've seen of the OP car, I do not think I'd change much. He has the best intake manifold and 65 heads probably flow better than most small port heads. Most good machinists will cast doubt on the need for hardened exhaust seats on Chrysler heads, especially when using stainless steel exhaust valves.