Aluminium line will be harder to bend into place with a body on the car, I did a 64 Malibu I had years ago w/ the body off .. wasnt bad at all. Braided line I have heard from many that fumes will seep out.
I changed my car over to braided line and never experienced the fume issue and parked my car with the rear 5' away from a gas water heater ... and my wife can smell a fly fart from 50' away and she never complained. So I dont know how valid that point is. I have probably used SS line from every supplier there is w/o issue.
I've also heard about the alum. line " work hardening " over time and cracking. I ran it on a street / strip car for over 10 years with no issues.
I'm pretty certain the Alum. line will need to be run through a steel sleave in the flywheel / flexplate area to meet NHRA specs. Thats what I did.
An FYI .. If you go the alum. hardline route, buy it from an A/C supply house and you'll pay about 1/2 of what a " speed shop " charges
Just passing along info I have experienced and heard about.