If you wanted, you could throw a 12v powersport battery(motorcycle, lawnmower) from the cheapest place and it would run fine, you'd just need a jump every time you wanted to start.
Let's start over. Does your LR start currently?

 

Interstate is what came in it from the factory.
I have a Duralasat Gold battery, battery brand makes no difference and the guy is giving you a line of crap.
The truck has no way of knowing what battery is in it.
As long as it meets the minimum CCA you can use whatever battery you want.
650CCA is the minimum you can use in your truck.
Keep in mind that most batteries are almost dead when you buy them, they loose charge sitting on the shelf.

If the alarm was already tripped when you unhooked the old battery it will pick up right where it left off with the new battery.

 

2007 Land Rover Range Rover want start got a new bratty still nothing change the alternator nothing everything keep going off no lights nothing