Alternatively you could find out what the root cause of this issue is?
I dont think there is an underlying problem, the engine is new so rings not bedded in and running 10.5:1 CR
On the breather pipe. How have you currently got that all rigged up? To the carb or have you hooked it up else where? Also how many other breathers do you have.
On the fuel smell, you sure the tank breather pipe is connected to the top of the tank and through the hole in the floor? Cuts out a load of smell, had mine come off one or twice.
Currently just got pipes from the breathers running in the engine bay
Fuel breather is attached and vented below the floor. However the small is not a pure petrol smell
If you want to feed it back into the carb then you don't need the breather, just run hose from all your breathers to the catch tank, then run one hose to the carb, to provide a vacuum, and help draw out the fumes from the crank case.
If you do not wish to send the fumes into your engine, then just feed them into the catch tank and fit a filter to it. If you currently have it like this then a line to a low pressure point under or to the side of the car would be your best bet I would have thought.
Having spoken the Calver I do not want to breath into the carbs now