In that picture is a soarer 1st gen r154. It will fit plug and play into an originally manual 92-94 SC300.
You do not have a 92-94 sc300. since you have a 95+, the tunnel has a hole further back so you will have to make a new hole in your tunnel more forward (where it is on a 92-94 SC400). Then it will fit fine.
If you absolutely did not want to make a new hole and had to come out of your current hole in your tunnel, you could sell that 1st gen transmission and get a 2nd gen soarer one with the Tripod shifter (basically exactly like your current w58) and that is plug and play on 95+ sc300's that were originally manual, no new hole needed.
You kind of seeing how 1st gen soarer r154 is plug and play on a 1st gen SC300 w58 car, and how a second gen soarer is plug and play on a 2nd gen sc300 w58 car. the generations match up and what you are doing is cross generation and that usually means a new hole in the tunnel or a shifter extension.
OR and I am saying OR again, If you absolutely do not want to make a new hole or get a 2nd gen tripod r154, you can extend your current shifter housing several inches and get a straight shifter made and it will come through your 95+ hole. This is basically what everyone does with mk3 r154's anyways but people like to do different lengths extension. like if you have a 92-94, you get it extended less and use the bent shifter, if you have a 95+ you get it extended more and use a straight shifter. I don't even know where you can get a straight shifter for these types of trans, maybe people are still using the bent ones but I would think a custom straight shifter would fit best.
Its really not that hard all the info is in this thread give it another read.
in this pic one is a w58 and one is an r154 but that is not important, what is important is that you get a visual of the 2 types of shifters and where the base of the shifter is. notice the tripod the base sits much further back. you make the hole right above the base so you can see how the hole for these 2 shifters would not be in the same place on the tunnel, even though both actual shifters end up in a similar spot. the tripod ones come up straight, and the older ones are always angled.