Fuel Tank Vent?

[Not Anumber]

When the previous owner changed the carb to one that ddnt need a return fuel line he left the hose where it was near the inlet manifold and just blanked it off with a bolt in the end. Is this adequate or should this terminate in a one way valve. Theres a Newton filler cap on the tank, not sure if these are vented.

[SeriesLandy]

I have a breather on the filler neck but also got kev to put one on the tank. I've put a one way valve on the tank and blanked the filler connection off with a stainless bolt.
Will this be ok for iva ect. I feel it's suitable but will others think otherwise?