First of all, thanks for sharing that link. It gave me some ideas for a problem I am working with...
Anyway, a 1" bore should be big enough. But, each application is different. You may need to go bigger. When I did mine, I tried a few before I got it right. But, I was working with cheaper parts.
The fact that you have to pump it up makes me think somethings up with the residual valves. Or still a possibility there may be some air still in the lines. That lower MC doesn't make it easy
Was this a kit or are you putting it together yourself? If it is a kit, is there a tech phone number you can call?
Sorry I'm not being very helpful here.