At first thought , if all the brackets are already set for say a 4" lift , the simplest thing to do (if you get it) would be to finish welding the lower control arm brackets and make the axle complete in its current configuration. Other than that , you would have to cut off all the other brackets reset your pinion angle for your 2.5" lift and reweld them for your current pinion angle setup.
Now if you do finish up the 8.8 for the 4" lift (and it should be fairly easy to figuure out C/A bracket location biased on the artec truss system. Artec can answer that for you quickly ) it would still work as long as you have adjustable rear control arms, adjustable track bar , SYE, C/V drive shaft , brake lines......
its just that your springs will be rotated at an arch slightly. Good thing would be that if you ever decided to to go a 4" lift , you would still be good. Now remember I said at first thought. There may be something Im missing, and the others can surly add to this.
You could always measure your current rear pinion angle and the rear pinion angle of the 8.8 (by setting the 8.8s spring perch at zero degrees then measure pinion angle) and Artec could help you from there too.
To answer your question "should you go for it"? Well I just can't answer that.