I have run this setup on the front in every configuration imaginable, to include Gen 2 shock with Gen 1 spring on an unmodified Gen 1 bucket. Can confirm that the IWEs, axles, etc also do not like being put at extreme angles like top perch or extra length of the Gen 2 shock without proper buckets.
If you are running KHC buckets, there is no reason to swap out the front springs, perches, or top hats. Just run the front shock with the new bucket as is and Gen 2 spring. I wouldn’t mess with spring swaps, perches, top hats, preload collars, or any of that stuff.
The Gen 1 springs are actually a bit shorter than Gen 2+ and your ride height will be quite low without the proper Gen 2 springs. To compensate and get the right ride height, you’d have to run some big collars or mess with the perches so much that you’d end up killing your bump travel.
With Gen 1 springs on Gen 2 shock, you also would need new top hats and coil insulators. The Gen 1 hats are quite funky on the KHC bucket because the threads are so long, since they’re designed to be ran with the angled rings.
My current setup is:
KHC front coil bucket
Gen 2 3.0 front shock
Gen 2 eibach
Deaver +3
+2” drop shackle
Gen 2 3.0 rear shock on OEM mount