One-off coilovers

What are the factors that make 1 coilover damper/strut different from another car's?

As many factors as possible would be great, to make it as clear as possible.

Is it possible to modify another car's coilovers to fit a completely different car by changing the mounting points?

This is something that could be done by measuring and having someone weld on new brackets, or are there other intricacies involved?

For my car it would be replacing something like this:
[img]http://img230.imageshack.us/img230/677/l300064461kybdc92bcwq5.png[/img]
(sorry about the tiny pic, it's a KYB GR-2 strut btw)

With something like the one on the right in this picture:
[img]http://img230.imageshack.us/img230/4544/teinflexkitldd1c6eit6.jpg[/img]

I'm just asking because if there is a way to modify another car's coilovers to fit the BH chassis cars, that would be an epic step forward for us.

The biggest factor i think would be is stroke. The distance the piston travels.
but this could be remedied with stiffer springs. Using the Z32 coilovers on the G50 i don't think the piston lengths are the same just tolerable enough for easy driving. I bottom out every now and then if i go over a speed bump too quickly. 
probably cause the stroke is shorted than say using coilovers designed for the car.