[Thomas]

I thought I had found the problem. The rubber fuel line which runs from the solid line coming from the tank to the fuel pump seemed a little long and appeared to have developed a slight "kink". It came as part of the fuel line kit that I installed over 10 years aago, so I never paid much attention to it.
I replaced it with a new and slightly shorter piece.

It took the car for a spin, and here is what I've found. The car "runs out of steam" somewhere around 4700 RPM, in any gear.

I have checked the float levels and they are okay.

Any ideas?

I was thinking of increasing the jet size in the carb.

Or...

Could it be an ignition problem like a weak coil?
The timing is set to 4 degrees and the dwell is 28 degrees