I am not sure about 300 watt, as that requires planning permission to use outside, normally 150 watt is the limit, but you could get converter bulbs
This one is claimed to be same light output as 120 watt halogen which would be just under the limit for planning permission, and called R7s.
But
Screwfix for example whole lamp at £4.52, bulb £9.98 so it does seems pointless to fit a LED bulb.
This one shown at £3.63 but not as bright and different length. I think the 300 watt was 118 mm?
If you look at
Screwfix site as an example you can get lamps at nearly £70 and 50 watt, 6000 lumen is a massive output, so it depends what you need.
I have just replaced two 150 watt I would guess flood lights, with two coach lamps, with just 800 lumen smart bulbs, positioned so I can see both in front of house and up the side,
it is not clearly flooded in light, it is a large area to light with just two bulbs, but it is enough to see from car to house and around side of house to front door, to get a PIR to control light around the corners is not going to happen, this was what was wrong with the original set-up, they would switch off when I was half way up the steps. So new bulbs are smart bulbs, so I can switch on before I leave the car, and off once in the house. So down from 300 watt to 18 watt.