Do I need to replace the horizontal shift shaft on my 9.9 hp Mercury?

[Valley Boater]

I'm in process of converting a 1998 Mercury 9.9 hp 2 stroker from a remote to a tiller / tiller shift model. I purchased the tiller and related parts on eBay and just started the conversion and am stumped with whether I need to replace the horizontal shift shaft. Here's the part that came with the tiller assembly and it corresponds with the part for the tiller and side shift in the parts manual:

I know I have a horizontal shift shaft as the motor shifted fine when demo'ed on controls. Here's the photo of the current installed shaft:

Am I okay to use the current installed horizontal shift shaft? I don't what to go through the process of uninstalling the current shaft unless necessary for the conversion.

Thanks in advance for any insight and advise.