Even my fibre glass hood from KAD had a hair lip luckily it made it easy to remove .

I'm with Malcom on this, rivnuts and proper screws. How often do you actually take the grill off....

Where are the pictures of the famous Hairlip?

I've converted a few - one of which was a show van ready to go to Goodwood that had the wrong front end fitted !

A spot weld cutter (Harbour Freight for a few dollars work very well) and a Roloc disc in an air grinder plus a steady hand and nerves of steel will see you right.

I use riv nuts and machine screws to hold the grille in place it gives a cleaner look than the grille buttons imo.

Mark Forster’s MK I Mini site’s for sale page carries proper reproductions of grille buttons. The readily available items aren’t nearly as good as the 1960s Speedwell item. Of course, if you have a lathe you can make them. With the originals there is no messing about as described above. Originals are 5/16” UNF and can also be used to retain valve covers. A half-moon can be cut from the lower edge of the grille slat for a clean install.

I did it on mine, you have to hope the hood piece has not chattered through the paint, mine polished out ok, then if you plan to use the mustache extensions, you have to drill a few holes for the clips, I think there's 4. I had flairs that prevented their use. Everything else screwed in place to existing holes, but I have a 62 car. I also went with grill buttons on an Austin grill, but had to make some black nylon spacers to fit over the studs, and between slats, to not bend/crush the grill using them, it does make oil changes nice.

Main thing is that you'll need to remove the lip off the hood..... ( don't want to end up with a hair lip MINI    )

Usually involves a bit of grinding, filler and paint

Anyone know what mods are required to swap a late model grill for the earlier mustache type? Thanks!