double or single flare?

[meatonastick]

I'm gong to replace all of the brake lines on my car ('62 fairlane) since they're either original, or at least very rough. My question is whether single flare will be okay, or if I should just stop being lazy and cheap and get the right flare tool? I know double flare are standard for brake and that single flare like to crack, but will that crack just result in a leak or will it result in me slamming into something at speed? eventually i'd like to get stainless line and do it right, so im wondering if a single flare will be okay for "right now" or will I just end up causing problems...

thanks in advance..