Shafer's Classic Reproductions
http://www.shafersclassic.com/
I've dealt with and they make a good product they re-sell to other distributors like NPD and mustangs unlimited.
they can also special make lines anyway you want, they make all the lines for our cars, fuel, brake, vent, and even the transmission modulator line, for c6,c4 and fmx.
when i installed the lines most required no modification to fit 100%, i had to do a little manipulation with the long intermediary line that runs under the car but it was minor. much of the issues i had was because i used stainless lines, mild steel would of been a very easy install by comparison.
as far as the rubber lines i bought those from Mustangs unlimited, i do not know the manufacturer they were a perfect fit and i had no issues. you could upgrade to braided brake lines if you wish. stock style was good enough for me.
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As far as what to replace that is up to you. you may find your hard lines are in good shape or not. I can guarantee if they are are original lines they will need to be replaced. I believe you posted about the line running under the car to the rear axle seemed to be leaking. take that as an indication that all the hard lines are rotted out from the inside. I can guarantee that once you start pulling off the soft rubber lines that at least one hard line is going to snap on you, this would be further proof to replace all the hard lines.
work slow and take photos for yourself so you can remember how everything goes back together.
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costs: i completely replaced my brake system in 2008 i mean EVERYTHING including the prop valve the cost for that was right around 3000$: Master, booster, prop valve, all lines hard and soft, new front calipers, rotors, pads, hardware, rear lines, drums, hardware, springs, adjusters wheel cylinders, new clips, converted to dot 5 fluid.
now unfortunately this ALWAYS leads to While I'm at it syndrome. You will always discover more problems while you are down there.
when the brakes are in poor condition you can bet the suspension is not far behind. ours cars are pushing 40 years old its to be expected.
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Since you are getting into your steering system i would recommend checking out your steering rag joint, and looking at your tie-rods and pitman arm and idler arm as well. everything just starts screaming replacement at you.
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Don't be scared, don't worry we are here to help photos and pictures say it all. Look at it this way, you could go to a mechanic who doesn't care and just replaces what he sees as bad, spend 1000s of dollars for his labor and then 4 months from now you slam on the brakes and the part of the system he decided was so-so and didn't replace so he could make more of a profit off you lets go and you loose half the brake system.
its your car and your money when it comes to brakes i see no reason to screw around and second guess things.