What's needed for stock steering wheel change?

I also think you need the S79 horn switch - it is the tilting of the switch, byt pushing on the horn ring that blows the horn. On a 70 rim blow nothing tilts so I think the horn switch is different. If you get stuck send a pm and I'll take a pic of the correct s-79 horn switch and you can compare with the one on your rim blow.

There is no extension can used with either of these wheels.