Both the Sinclair ZX Spectrum and the Pac-Man arcade machine used the Zilog Z 80 CPU.
Pac-Man's display was slightly larger and vertical at 224×288 while the Speccy's was horizontal at 256×192.
The Speccy did not have hardware sprites or pixel-addressable colours.
The original 48K Speccy only had "1 bit" beeper sound though later models had an AY sound chip. The arcade machine had a Namco PSG sound chip.
But if you're willing to scale down the graphics just a tiny bit and put up with a bit of colour clash when different coloured things are too close to each other, you should actually be able to port the Pac-Man arcade ROM code to work on the Spectrum hardware.
No need though since Simon Owen already did exactly that nearly a decade ago:
It's not a port. You need to provide the Pac-Man arcade board's ROMs. It runs the ROM code and just emulates the hardware differences. As a nice coincidence he just released the first update in four years this March.
By the way:
I just discovered that somebody has actually done the opposite of this too. The early Spectrum classic game Manic Miner was converted to run on original Pac-Man arcade hardware! Also almost a decade ago.