The LT1072 Datasheet (page 9, attached) shows how to synchronize the device's switching to an external clock by using a BJT or FET from Vc to Gnd.
Can the LT1070 and/or LT1074 be synchronized using the same (or similar) technique?
If the datasheets have no description of it, then no.
I believe the below parts have the SYNC pins.
I just tried the LT1074 in LTspice and synchronization seems to work if you drive the SHDN pin. My LTspice circuit and simulation results are in the image below. I'm sure there are limitations to this technique and I don't have any LT1074 hardware at the moment for a bench test, but the LTspice results show that a bench test is worth trying.