[TP2SS]

Just find a used '17-'19 ZL1 and be done with it!

You'll have your 550+ WHP with no mods, and a full powertrain warranty for 5 years from original in-service date. After that ('23+) you can mod all you like and end up with 700+ WHP easily, and the LT4 can handle it.

Think about what you're going to be putting into that "new" LT1 to get you to your 550+ WHP goal:
Initial cost: 40K (?)
Blower kit: 8K+ (probably 10k+ if you can't install it yourself)
Wheels & tires (b/c the stock 245's aren't going to like 550 WHP): 3k+
Exhaust: 1-2k (?)

With just those you're up to 53-ish+, and you have a car with a voided warranty, no mag ride, and LT1 internals that will never withstand more than maybe 700 CHP without further changes.