Windscreen washer knob markings (and a little additional plan!)

My car's not currently fitted with the windscreen washer, and the appropriate dashboard hole just has a rubber grommet. (The shroud had two open holes for the jets, and I've fitted a couple of new washer jets into these holes now.) In the boxes of parts that came with the car I've found what must be the original Tudor washer pump, but there's no knob on it. Should this knob be plain, or be marked with a "W" or "Washer" or something similar?
Incidentally the wipers (and presumably the washers) are so anaemic in an MGA, I'm planning to utilise the washer bottle reservoir as a radiator overflow reservoir bottle instead! I'm fitting the jets and dashboard pumps so the holes already there look appropriately filled. I'll refit the washer bottle and cradle where it would originally have been and run the hose sneakily forward to the radiator overflow inside the guard. Not sure if my plan will work, and the washer bottle's smaller than ideal for this purpose, but do you folk think this might work?

Tom have you got some spare time at the moment.
Unless you have a recovery neck and cap on the radiator i dont beleive it will suck the water back into the radiator. I have a bottle infront of the radiator which fills but doesnt return. So i tip it back in. Very basic.
I did have a screen washer bottle but removed it as the wipers were so weak they only spread the water and not cleared the screen.

Not sure about the switch.

David, I have seen some knobs in white (not correct for the MGA IMHO). Also some with the Tudor brand engraved. Mine is the made from same dark bakelite that all my other MGA knobs are made from but without the Tudor name. It matches the patina perfectly.

Clarke has them for less that $5..
They are also availible from Holden at a higher price.

http://www.holden.co.uk/displayproductsByMake.asp?carMakeCode=M5&carMake=MG&pageno=11

Thank you all. I'll get a knob like Chuck and Gary have shown from Clarke's. I was going to put an order with them sometime soon anyway, as I was intending to buy the parts from them to fit seat belts to my car.
As for the idea of using the washer bottle as a radiator overflow reservoir, as usual, someone's already thought of it first. My discussions with Barney Gaylord however indicate that this is quite achievable despite the marginal capacity (for this purpose) of the washer bottle.http://mgaguru.com/mgtech/cooling/cool_204.htm

Good Day MGB 65B.
Re-your need for an MG A Windscreen washer knob---I have a knob in mint condition--attached to a vaccuum pump, with does not seem to work.
I am on the Gold Coast--perhaps you may wish to phone me on o7-56681937
At the same time, I can steer you correctly, in relation to your radiator recovery container
I have been slow in contacting you, due to computer miss adventure.
I look forward to your contact.
Ian.

My 1600 Mk-II came with a white Tudor windscreen washer knob when I bought it back in 1985. No idea if it was original to the car, but I've certainly seen other MGAs with white windscreen washer knobs. The repros are all black; I've seen white ones occasionally for sale on eBay and they seem to get snapped up rather enthusiastically.

Speaking of washer bottles.
What is the correct location for the bottle. I've seen the by the makers plate and also by the heater..