Your Heat Lamp is just fine in the fixture its in. You could even replace that coil bulb with a second low wattage heat bulb. Honestly better than the domes most folks are using much more spread of light, and a more even heating of the entire top area.
No offense meant to anyone, but people tend to get stuck into a pattern of black and white. As we see with screen cages a lot (surprisingly not in this post, yet

but thats been changing slowly). Something is recommended as it works, the "Dome" or the "Screen Cage" and suddenly everything else is the devil, and that gets rehashed and repeated from there on forever.
The Exoterra fixture you have those bulbs in, reflects heat, it reflects light, put basking lights in it and your fine

, it wastes a little more heat and the "Dome" shape, but in your case especially that is okay.
Huge disclaimer, this isnt the case for everything. That Coil bulb is garbage, for the same reason I would use your hood over that "Dome". Its a very small Beam of UV light, with a high concetration of UVA, and pinpoint UVB, so its worthless outside of its circle, and is dangerous when you look at it, or when the animal does, it can cause "Snowblind" or "Welder Flash Burn" when looked at directly especially for prolonged periods.