Surface Mounted Round Plaster Downlight

Would I be able to have these fitted over a 60mm cut out from a previous flush downlight?
Unfortunately the distance of the fixing holes of both of these fittings are 60mm apart and therefore although the fitting itself would cover your cut out, the fitting will not be able to be sufficiently fitted to the ceiling.

Could I use these mounted horizontally on a wall to flush light across a ceiling? Say mounted at 2.85m above floor level would the bulb be visable or would it be deep enough in the plaster fitting to be obscured? I want to fit lights above a protuding cornice to flush light right across a ceiling.
The length of the room will determine if you can see the lamp. Long room and you’ll easily see the lamp, short room and it will be harder to see the lamp. We would suggest a narrow beam LED lamp and either a honeycomb filter or cross louvre to reduce glare. Try a mock up first to understand what a bare lamp would do in the space.