A few years ago I made a flame cherry cabinet top that was about 18" x 84" x 1" thick. I only had one really nice 8" wide flame cherry board so had to come up with a way to make that one board into the entire top surface.
The solution was to resaw that board into three 1/4" layers that were glued to the face of a full width cherry blank I'd made out of non-figured cherry. I then profiled an edge detail (using a raised panel cutter) that hid the seam between the flame upper layer and the main cherry sub-surface.
This worked really well and the top has been stable for the 3 to 4 years since construction.
You could take the same concept and increase it to the thickness you require. However I'd be concerned about any 2 1/2" thick solid top unless handled correctly. If I were applying 1/4" to the top of a thick solid core I'd be inclined to apply a 1/4" layer to the bottom as well. That will give a glue line moisture barrier 1/4" in from both faces. I'd also want to use very stable boards for the core.....or perhaps edge glue 3" wide boards together to help in stability.
The alternative on the core is to make an approximately 1" thick top and band it with a thicker edge applied to the bottom surface around the edges. The ends would need end grain strips glued on as vs. picture framing the ends with length wise boards so they will expand and contract with the rest of the top.
BH Davis