The RCP NUS chip has a FIRMWARE rom.
The CPU-NUS has a built in ROM as well. They're identical for all N64s.
The bits of ROM on the PIF chips though vary per region.
The cartridge ROM chips are custom and use an proprietary multiplexed bus.
So NO, you won't be making repros of N64 carts unless you own a chip manufacturing plant or know a LOT about FPGA and design...