1972 Cb450 stainless steel lines now causing a leak ?!?!?!

Finally bit the bullet and got stainless brake lines for my 1972 CB450.
After the initial installation I developed a leak at the Master Cylinder.

Ok. Prob needed a rebuild, got the kit did the work and I still have a seat of brake fluid coming out from the lever screw.

Can stainless line produce too much pressure causing a leak, even after a rebuild ?

Can anyone suggest a swap to something more current that can handle the increase in pressure ?

thanks

Pulled the lever and wiped up everything, no leaks overnight.
Installed what I call a master cylinder tampon and rode into work....no leaks ?

It's hard to imagine that this was residual from the repair, I could swear I cleaned it all up.

I've also got a Grip Lock on the throttle side. I wonder if the slight constant pressure on the brake system while parked it causing a slow leak ?