Dash 10 seems to be the common size
my oil cooler setup uses Dash 10 also. I am yet to install it but have faith it will be o.k. worth installing a pressure guage in your sandwich plate (most have provisions for this) to keep a good eye on it.
I actually have a question that is sort of relevant.
when you have installed a thermostatic cooler and start the car for the first time, once it reaches the required temp for the thermostat to open there will obviously be a massive pressure drop whilst the pump fills the lines, i will be pre fillling the cooler as best i can but am concerned at the drop in pressure as the lines are quite long and as mentioned above the hose size isn't exactly small.
any way around this or is it a non event??