line lock not releasing?

whats would be the benefit of flares over the fittings i have now?
the ones i have now are rated at 10,300 PSI

Don't worry about changing the connections as they are plenty up to the job as long as they are good and tight, and I have to agree about the unit being bad. (you could bench test that once it's off)
On my 73 I have it right out of the master cylinder like you saw in the pic I posted and have zero problems with it.