The engine itself has nothing to do with the speedo cable.
If you're using you N/A trans then you'll be fine.
If you're using a turbo tans from a 991-92 you'll be fine.
If you're using a trans from a 93+ and have a 91-92 guage cluster (mechanical) then you will need to find a speedo gear and assembly to swap out the 93+ electric one. The speedo gear assembly is interchangable between mechanical and eletrical.
Hopefully that helps better. The cable screws into the assemebly wich is located on the diff housing part of the case.
On a side note, Ben does your car has Power steering?
Your pin out was fabulous, but the "RLY and PSCT" I do believe are backwards. I fought my power steering until I double checked with another pin-out diagram
found here.
Just thought I would bring it to your attention. Thank you for the help your thread gave me too. I got my 93+ JDM trubo swap up and running with no major problems.