Speedo Cable/ Grease Cap Issue

[BWE]

I ran into the same problem when fitting 16's on my '70. My wheels came with little snap-in centre caps. The fit was very tight so I just squeezed extra grease into the passenger side bearings and tapped the cap on. On the driver's side I fabbed up a thin strip of aluminum with a square hole (just big enough for the speedo cable end) that is pinched under the cap when it's installed on the wheel. I did have to spend some time clearancing the underside of the cap and forming the strip so it wouldn't show. So far it seems to work well... time will tell.
If I can I'll try to get some pics this week.
Hope this helps,
Dave