Comparing images on this post with the carbuilders one, the slotted hole looks to be further in than the original round hole position, so it could mean that they will be a better fit without additional drilling. Be interested to hear how you get on.

Doug
2011 Plus 4 in Rich Maroon

1972 750 “ComDom” sprinter
1958 Triton 650
1992 Triumph Trophy 900