Could really use some transfer case help please

[Zigy]

So it's like this..
I have a 1979 gmc k2500 that I'm trying to do a conversion on the drivetrain.
It has a Th400 with a 203 in it. I'm trying to change it with a 700r4 and a np241c . I have bought both already and here is the problem I have now.
It took me forever to find a 241c passenger side drop out here but I did.
Problem is that it's VSS.. How can I make it a mechanical speedo ?
Please help me figure out this problem.
Thank you in advance

Do you think if I could find a busted 241c and replaced the speedo gears and shaft sleeve it would work? If so, would it matter if it came from a driver or passenger side drop case?