My CPU design calls for several multiplexers that allow the output to be selected from 2 different input values. For example, one of the inputs to the ALU is chosen from either the program counter or output port A of the register file. The design for this is pretty trivial.

I use 8 x 74HC241 to perform the actual switching of 2 x 4 input bits to 4 output bits. With the constrained PCB size of 100m x 80m we have enough room for the first 32 bit input at the top and the second input at the bottom of the board. With the IC's in the middle we have the bottom 16 bits output on the right edge and the top 16 bits on the left. So the PCB is very busy with headers around all the edges and filled with IC's.

You can see the mux board at the bottom left of the image...

I am only testing with 4 bits in the image. So the first input is 0xC, the second input 0x0 and because the selection bit is high the output is 0xC. Now I just need to order enough headers and IC's to make another 5 or 6 and I should have the mux requirements covered.