That's not a real dilemma, is it
You want the ZL1, otherwise you wouldn't ask the question.
The extra power is always welcome, but know that you won't be able to go WOT that often and for long on public roads. If not being able to use the available power 90% of the time frustrates you, think again.
The ZL1 is clearly superior to your 2SS (although I will say yours looks very, very nice as-is), but it's not a "completely different car" at "another level altogether" as some ZL1 owners invariably claim here, it's a Camaro still, not some miracle McLaren 720S-like creation. Set your expectations realistically, and you'll love the ZL1.