Can't Get a Solid Brake Peddle

[ace347]

So I have a bit of a mash-up of parts. However, It all worked fine once before. I have a 71 chevy truck that has been retro fitted with hydro boost from an 08 Chevy express van. Since the van master cylinder didn't fit under the hood, I used a refurbished 95 Chevy truck master cylinder. I put it together about ten years ago.

I added a Hurst roll control cylinoid to the front bake circuit. Now I'm tryin to bleed the front brake circuit and the brakes won't firm up. The brakes pressures up until I start the engine. I get some pressure at the peddle but with a little effort I can push the brake peddle to the floor. When I turn off the engine and the brakes will hold pressure. I don't have any leaks that I can find, however, the bottom of the master seems to always be wet with brake fluid. But, this could be from the mess I keep making when trying to bleed the system.

One thing I have noticed is that when I forget to put the master cylinder cap back on and press the brake peddle, brake fluid shoots out of the reservoir. I was wondering if that was normal?