Hi,
the LM1084 should work fine in place of the LT1585, just double check the pinouts.
ESR (
www.esr.co.uk) sell Crystal oscillator modules at 50, 64 and 66 MHz in single quantities. Rapid Electronics (
www.rapidelectronics.co.uk) sell 50, 66 and 80 MHz oscillators.
The LTC1430 is a switchmode power converter controller, unfortunately discontinued by RS components!
You could try requesting a few samples?
