EL;
I would definelty put on a smaller diameter water pump pulley,the water pump pulley should be at least one inch diameter less than the crank pulley.... I have expiremented with this for a year on my Mustang.... March and other pulley makers as well as the makers of water pumps will tell you the same......look at your wife's car and see the difference is pulley size, you'll be suprised!!!!!!!
As for the water puking out of the tank, dat don't look good!!!!I've seen this when all the air was not purged from a system...... I would try removing the thermostat altogether and put a water restrictor. You can buy the kit for a few bucks from any dirt track racing outlet....It looks like a very large washer with a hole in the middle, usually you get three, with varouis size holes.... see how that does along with a pulley change.
http://store.summitracing.com/partde...0&autoview=sku
I think you have enough radiator and cooling fan capacity, maybe a radiator flush just to be on the safe side....In all my vehicles I run a gollon of anti-freeze and fill it with water, usually about 2 to 3 gallons of water, never had any problems and thats about 25% to 35% anti-freeze, that's all you need.....
When I was testing different pulley sizes on the Mustang, I would leave the radiator cap off and start the car and let it get up to temp and watch the coolant flow thru the radiator, with the same size pulleys, the flow at idle was suprisingly low, the water would come out the tubes maybe a half inch, rev the motor to 1500 rpms and it would come out 2 inches and that is with a high flow,top dollar aluminum water pump!!!!!!!!!!!
I'm guessing slow water pump speed and possibly air in the system....
Are you sure the fan is turning in the correct direction?? (puller or pusher)(puller works better than a pusher)?? Some fans will turn either way depending on which wire is hooked to the hot and ground... If it runs hot on the highway, but you can keep it cool with a garden hose at idle, that points to a fan that is running backwards from what it needs to be.... I've done this before myself and have seen it done a number of times... check the easy stuff and double check it all.....
David