The cycleX tubes will not fit a 71 (K1) bike. The pre-K2 bikes had completely different fork internals from the later ones.
Your best source for new tubes will be Franksmaintenance aka Frank's Forks aka Forking by Frank. They will have the stock lengths.
http://www.frankmain.qpg.com/From the site: "There is no other after-market manufacturer of German, Spanish, or Japanese fork-tubes." I don't think they are lieing. I think everyone buys their tubes from Franks, incl CycleX. JMHO OCICBW