It all depends a bit on the lighthead.
If it is one of the first, the head was bigger than the later ones. depending on the inside diamter, you can select the optics.
In the smaller ones, I used 3 XR-E's with fraen reflectors and overdriving them at 1.2A, while the bigger one could support 3 XPG's with ledil LXP optics. I just re-used the original heatsinks, although I modified one of them slightly as it had some metal sticking through the PCB to make contact with the LEDs. I just removed these pieces and was good to go.
If you can post a picture, or a link to a picture of your particular head, we can be more precise. Giving the inside diameter and the available height above the heatsink helps to determine the possible optics.