Hi Clois,
Getting a good builder I guess is part of the trick!
Not many people in the UK know much about FEs.
I have confidance in the guy I'm using though, the engine definately ran better after the new rocker shafts were put in and the lash re-set.
The last time it was built (before I had the car) the lash was set way too tight! Makes you wonder what else they did wrong!
If in doubt, hit it with a big hammer!
Cheers
Paul