Fuel Line Copper? Is this OK or bad? Goodyear SAE 30R9 Options

[kbrunk1]

I am trying to get a 2.0L FI running again and have soft copper which is for air conditioners. It is usually thicker wall than ordinary 3/8 in cu (for AC stuff)

It seems that SAE 30R9 is what the forum recommends.
Has anyone tried using soft 3/8 cu and then just use small 5/16 30R9 jumpers?
Will 5/16 30R9 slip over 3/8 without problems. In effect make the 3 ft runs across the engine out of copper.

My idea would be to buy the 10 ft roll SAE 30R9 5/16 off ebay for $45 and try to redo the blister, the area under the fuel tank, the risers from the ss down the rail to the upper part of the engine and then the two across the engine.

Any idea how many feet of fuel line is needed for a redo? 5/16 30R9? I bought the 5 piece SS 8mm kit to convert a 73 to a 74 type setup. Came with the 2 long picecs down the rail then two "risers"
and an adaptor (converts smaller line from tank to 8mm?)
Advice is really welcome !