Replacing rb20 cluster with HUD help please

[mocmiranda]

Here's the thing , I have a rb20'd 240sx dohc .
It has a rb20 cluster already installed and spliced into
The dash harness . It was never hooked up with the speedo cable (analog).
I know im going to have to splice the HUD sub harness into the dash harness where the rb20 cluster was spliced in , do all the wires match up? They seem to be the same colors more or less. Also what will I need to get speed to read on the HUD ?
Will I need to get the speed sensor from the ka? Will it fit the Rb tranny ? Any other help will be appreciated . Also if u can't help just move on. I don't want to get slammed. I spent hours searching for answers and haven't found a problem that fits mines ,so I come to all u great Nissan experts for help ! Thanks ahead of time .