If you wanted to stay with the colour and pattern, you could probably daisy-chain two Heritage hoses together? The nozzle end fits snugly into the machine end.
Not all Kirby hoses are the same diameter.
Tradition and Classic 3 are both narrower than Heritage/Legend.
Heritage/Legend are narrower than Sentria/Avalir...
You can get extra-long stair hoses for Sentrias (I have one) but you're going to be losing suction the farther you go. Most users say hoses are a significant loss of suction as they are.
Could you not just use your Kirby Legend II hose (6') & tube (2') plus elbow, to reach 8'?
I've lubricated my belt-lifters with 3-M ® spray-on dry silicone lube. Designed to lubricate bicycle chains. It dries to a slick smooth waxy finish. Be sure to dismantle and clean your belt-lifter first, to remove any dust and grit.