A custom solution is required in order to play all the Aleck64 titles. The cartridge you are tinkering with "PCB-2A" from Vivid Dolls, has 3 chips on it. Upon closer inspection and some google, you'll find that all three chips are propriety, unique parts that cannot be purchased.
NUS-ZSAJ = Maskrom, it has pins labeled as AD0 to AD15, ALEL, ALEH, /RD -- where as a standard memory chip has A0 to A31, D0 to D15, /CE, /OE. So this is why a fpga or additional logic is required, as the nus maskrom uses ALE (address latch enable), which means the n64 cpu provides the data address on AD0 to AD15 in two parts (ALE, low, high) to make 32bits. It then strobes the /RD signal and the data is output on AD0 to AD15. Each time the /RD signal is strobed an internal address counter increases so the cpu is able to consecutively request up to 256 words of data.
BK4D-NUS = also known as BU9850. 4 kilobits (64 words * 64 bits = 512 bytes), serial eeprom that uses a custom protocol.
CIC-NUS-5101 = This is a microcontroller that functions as the security lockout chip. There are many variants of the CIC, both for regions and specific games used on the retail N64. We didn't know how to properly emulate this chip until around 2016. Ironically, the 5101 is actually unique and slightly different from the algorithm that was used in the retail CICs.
So with that explained, you could use a donor for the BU9850 and CIC, but you still need a custom solution for the Maskrom. Which leaves you with may as well roll something custom for all three parts.
I'll show you in a few days what I've been working on