Does anyone know if there is a fuel tank fitting (simple barb like on a late beetle) that bolts onto the outlet and would eliminate the reserve tank control valve on an Oval bug tank? Mine seems to be leaking slightly so I want to sort it out.

Bump?????? Would a late model fitting bolt straight onto an early tank?

You just need to check out the thread size and then look for hydraulic/oil brass connection. Maybe even the aluminium areoquip braided hose fitting would come in that size.

I tapped the outlet hole in the tank to 1/4" BSP....plenty of grease on the tap to collect the bits of metal. A 1/4" BSP hose tail to suit your rubber hose will be easy to find [Pirtek, etc.], and your original tap can always be re-fitted, if required.

Or replace the tap fitting with a normal beetle fitting as you suggested, they are interchangable. Or you can tap out a nomal outlet to 3/8 BSP for a barbed fitting similar to what Greg has suggested but into the fitting instead of the tank. Or buy one of these, available in -6 or -8. http://www.piersideparts.net/CB3288.html