Help please with timing; uprated cam

[malcolm]

I'd be grateful for any advice on this; I have a 1969 series 2 4.2
The engine always ran as sweet as a nut, with no misfires, no hesitation, no hunting.
After a recent piece of work involving removal of engine, it now runs quite rough with hesitation at low revs on accelerating etc. The carbs weren't touched, so settings weren't changed at all. The timing obviously had to be re-done, and was set to standard settings. Thing is, my car has slightly uprated cams fitted by Rob Beere, (SU spec cams) and I wonder if the timing should be slightly different (more advanced?) with these cams?
Thoughts would be appreciated