Why would you want to? Surely the idea is to run as much C64 code as accurately as possible?
Widening the CPU instruction bus & data bus is pointless. All you do is introduce huge binary incompatibilities.
What you can do is :
Up the CPU clock rate.
Lower the instruction timings (fewer clock cycles per instruction).
Lower the RAM R/W timings (fewer clock cycles per read/write).
But each of these just introduces more incompatibilities.
You'd could have these features but perhaps make it a turbo mode which could be switched on specially for software which supported it? But then that means writing new software.
