I mounted a similar led headlight in the stock bucket using a cb400 retainer ring/rim assembly. Had to drill a hole on top and slightly shift side screw mount holes. I fiberglassed parts of my stock bucket and filled original mount holes. Then redrilled new holes. The fiberglass also reinforced those areas of the bucket.
Be sure you are getting the "good" version of this light. There is a shitty copy of this light out there. The shitty copy is shitty. The running lights will not remain on when low or high beam is on. There are some clues. Shitty copy has only 9 leds in each of the running lights. Good one has 12. The good copy has a compression fitting sealing the cable loom on the rear of unit, see pic. Shitty copy cable just runs through a rubber plug. Good unit has more venting on rear and a better seal on lens cover.
These light units have three keys on the rear that the cb400 retainer ring clamps. I also moved some of my stock wiring loom out of the headlight bucket and into the void left behind from the pair valve removal. That gap in the frame near steering head. I covered the wiring with those rubber pads that clip in there. Be real careful when drilling those three mount holes. Try the unit in there first and have a good look it's all square. Mine ended up a couple of degrees out. No one else has noticed it just me but I think it sux. These lights are about 60w and bright as f..... I got a pair deal as well and just keep the other for a spare. I like em. Running it for about a year now, no worries.
The light is great. Very bright. Low beam has a good cutoff and high beam pattern is more concentrated and very bright. See pic. Low beam on left, high on right. Also has running lights for extra visibility during day. I'll never go back to stock again. IMO it also looks cool!