Thanks for all your help,
I bought the car with engine fitted and was told it was out of a saloon car. The only upgrades that have been done to the engine is the fitting of a stainless exhaust manifold and sports exhaust. The problem I am having is getting a stable reliable tick over, without the engine cutting. I have replaced the distributor and the electronic ignition module. The carbs have been rebuilt completely, plugs, leads and distributor cap have also been replaced. I have reset the valves and checked cylinder compression pressure and the tick over problem still remains, hence the focus on the cam. As I will be taking the gearbox and overdrive out shortly to be rebuilt, I thought it might be a good opportunity to deal with replacing the cam. I will take all your advice and contact Newmans for their views.
Are there any other performance upgrades that I could do without having to get the engine rebuilt. Would fitting a stage 2 head be of any benefit.
Thanks again for all your help, Mark