If you’re looking for lift, the spring lengths are what you need to focus on. The gas strut/shock only acts as a damper to the spring, it does not increase the height. The 2 most-important measurements when selecting a strut/shock (not springs or coils) is:
1) the overall length (to make sure it is within tolerance of whatever spring you choose) &
2) the stroke length of the strut/shock
The idea is that the gas strut/shock can fit inside the entire strut assembly (spring, strut/shock, collars, etc) when put together and neither bottoms out under total compression of the spring nor tops out under total extension of the spring.
Hopefully this helps shed some light- I have experience installing coils and struts on vehicles that have no direct replacements (imported Kei cars from japan) and had to purchase the parts completely relying on stock measurements including, lengths, spring rates, stroke lengths, etc.