Is it possible to extend LVDS and SPI to 3 meter distance
If the SPI data is in one direction only then yes, it can be done. The problem with bi-directional SPI is that reading SPI data back from a slave (remote device) requires that the clock doesn't get too much shifted or the data returned becomes unreadable. 

At a master clock of 72 MHz, the period is only 13.9 ns and if the overall delay from sender to receiver back to sender approaches anything like half this time then the sender (master clock generator) is unable to adequately read the data returned due to the accumulated delays.

So, given that signals will propagate at about 5 ns per metre (light is 3.333 ns per metre), bidirectional SPI at a clock rate of 72 MHz will start to be unreadable at just over 1 metre.

However, if the data is "send only" then providing the SPI clock and data is driven down two coax cables correctly\$^1\$ and line receivers are used at the slave-end then the distance that can be achieved is limited only by the cable quality. Hundreds of metres can be achieved with good coax.


  LVDS data @ 720Mbps


This can be done providing you embed the clock with the data either by Manchester encoding or scrambling techniques - I've transmitted data (using proper line drivers and terminators) over 50 metres without too much hassle at this sort of speed but, it's down to using good coax (75 ohm 11 mm or greater OD) or good twisted pair cable.



\$^1\$ By "correctly" I mean using proper coax drivers with line terminators or maybe even using balanced line drivers and screened twisted pair (plus terminators).