This weekend I made about 100 miles with the car , and I think my problem are the lifters anyway and will go for the mechanic route...

The car has power, but as said, the engine dies at about 5300 rpm. The sounds changes and the engine loses power. I had a weber DFT32/34 carb and the engine had exactly the same symptons. Because of that I suppose the lifters are crap as they are making quite noise.

Before this setup, I had previously the DFT32/34, but with standard cam and lifters and the car has not that problem.

Now my problem is finding anyone that will supply the set of mechanics here to Spain.
Also I have seen on the newmans catalog, they have a tool for adjusting the followers. Maybe that tool will be quite useful for adjusting the followers.