I know people have installed these before but I thought I would show some pictures of the fit of the Corbeau LG1 seats in my '72 240z.
Corbeau bracket #C22011, mounts easily, no modification necessary. I used 35mm M10 bolts, Class 10.9 which fit the Datsun holes perfectly.
Bracket mounted. I needed to disassemble the bracket a bit to get the bolts in.
Seats installed. I used two small washers to lift the back of the seat up about 4mm.
I was worried about the seat width but they do not touch the door at all, there is a good gap.
They aren't too tall, similar to stock.
The colour appears blue in the photos, but it is black cloth. Material is good, better than I thought it would be.
Of course, they are a huge improvement over stock and provide a lot of support. I chose these over the Corbeau TRS or CR1 models as they have lower seat bolsters making them very easy to get in and out of. They are also fairly light, I didn't weigh them but felt close to the stock weight.
A number of people have modified the seat mounts to lower the seats in the car but I didn't feel that was necessary for me, I have about 1-2 inches of headroom. I am 6' tall but have longer legs so maybe that is the reason. I haven't put many miles on these yet so we will see.