Alan,
Yes ,Deffinately fit sealed bearings to wheels.Ive been doing it for decades now.Ideally you want the 2RS type (2 rubber shields) ,But the 2ZZ type (2 metal shields ) would be the next best option. From memory I think the conical hubs take 62042RS ball bearings. this is a very common wheel bearing on BSA's and triumphs.
Also,When building up gearboxes on a bike ,I always try to fit a 1RS type bearing to the main bearing that supports the sprocket (4th) gear.
If you fit it with the rubber seal outboard,then pack in some grease ,then fit the oil seal you then have a gearbox with 2 seals. Better than new.
If your bearing stockist doesnt hold a 1RS bearing then get a 2RS and prise out the seal on one side with a small screwdriver .
You use a single sealed bearing so that the gearbox oil can lubricate it.So make sure it is the right way round.
Mike