The water under the dash & The temp guage rising then falling could be caused by an air lock in your cooling system.
Try idling the car for a while with the radiator cap off and see if any of it bubbles to the top.
Just find a set of the twin aisan down draughts.
They pop up on here and E-bay frequently and you'll get em chesper than what you're willing to pay for two webers
Hey Ben,
If that's the same mechanic we were talking about the other day he failed me on a windscreen twice. (before and after buffing)
I'd be making sure he'll definately pass it after a buff/polish