The default SRAM address for the LPC1778 is at address 0x10000000 - 0x1000FFFF.
Is it possible to relocate the SRAM to be used, to address 0x28000000 - 0x28FFFFFF(SPIFI memory mapped access space)under target options in uVision by just specifying the new address for IRAM1?
Note: I wont be using SPIFI.
I want to mimic the SRAM at a different location by changing it in the target options.
You need to get the terminology right.
You're not mimicking SRAM, you're not relocating SRAM. You're just trying to position data and stack at RAM in a specific location different to where it was before.
So long as there is RAM in those locations and it's not being used for any other purpose, then you should simply be able to set the project options to locate those items at those locations.