I dunno for sure. I have same setup on my '69 GTS and it is pretty "Mickey Mouse". Lots and lots of pumping for a very weak spray. Not good. I think if you really plan on using those washers much I'd get the conversion to an electric pump!
I figured it out. The seal is made between the bladder and the mounting bracket not the plate and bladder. Once we start putting it back together I will explain better. We will see how it works. We got the electric with the Dart so I have the switch to make it work.