With my array, I had two KLM-14C for 145 MHz & two KLM-18C for 435 MHz.  The Yaesu/Kenpro rotator allowed a long boom, with one of each on either side.  I used RG-11 (75 Ohm) coax for the matching sections.  With a velocity factor of .66, the 2m sections were 2.25 wavelengths (9/4) or 360.6 cm (~11.8 ft) long.  The .7m sections were 3.25 wavelengths (13/4) or 174.8 cm (~5.7 ft) long.  This allowed for a little slack in adjusting the physical spacing between each side of the pairs.  I compared the 2m beam spacing at 1.05, 1.25, and 1.39 wavelength - and found lowest SWR at 1.25 wavelength (101 in).  The SWR for the 435 band was influenced by the 2m antennae spacing, but was generally lower and broader, the further apart they could go.  I settled for 2 wavelengths (54 in).

  Then bringing each pair together with a standard coax "tee" connector, I used 50 Ohm cable (9913) to make the rotor loops, and deliver to the tower mounted preamps.  For these relatively short pieces, I used multiples of half-wavelength, to ensure 50 Ohm.  For the 2m side, this was 1 wavelength (2/2) - 172.6 cm or about 5.6 ft.  The .7m piece was 3.5 wavelength (7/2) - 202.7 cm or about 6.6 ft.