PMOs on a Euro.

[dagriff]

I have a '77 2.7 CIS from the U.K.
The engine was re-built somewhere between 5-8k ago by one of the UKs best known blokes, so I don't want to tear it apart yet. However, I do want to go with PMOs.
I have heard tell that a Euro or ROW running the original (CIS) cams & old style exhaust will benefit more from just PMOs than a U.S. spec motor would with no other changes.

Is this likely? Would it just be the exhaust making the difference?

I will eventually go with a new cams but for various reasons the PMOs would have to be the first step, And I was just wondering what to expect (or not..)..

BTW, I looking for more mid-range from the cam choice, any recommendations?
Thanks in advance.