IIRC, the Trek catalog showed the frame dimensions for all frame sizes in 1979 for the 710. Check the wheelbase against the brochure. If the price is right, could be worth it.
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72+76 Super Course, 74 P-10+ 79 Tandem Paramounts, 84 Raleigh Alyeska, 84 Voyageur SP, 85 Miyata Sport 10 mixte and a queue