I replaced my 68 Camaro single line a few years ago.
With engine installed, without loosening any subframe bolts.
For me a few key points are, Flaten-straighten out the shipping bend per mfrs instructions, use the FLOOR and unwind the bend.
I took the hack saw approch for the old line removal and made short work of the rip out.
I jacked the car up on the passanger side VERY high and secure to give the most approach angle for hreading the new line thru the subframe to body gap at the front of the door, you need some height to work with when twisting and winding threading the turns of the line thru the narrow gap. I DID have to put a very slight installation bend while getting the front installed. I then massaged out the minimal installation bends to recover the correct as installed layout.
Take your time, I did it alone but another set of hands would have been VERY apprecieated,
WALK away when you get frustrated! Have a beer and come back to the task later.
Many have done this.
Steel line, I do not care for SS material lines and would not recommend them.