My goal is 450 hp. LS1/LS2/LS3?

 

If you can afford it, the LS3 makes close to that stock.

"The LS3 was introduced as the Corvette's new base engine for the 2008 model year. It produces 430 bhp (321 kW; 436 PS) at 5900 rpm and 424 lb·ft (575 N·m) at 4600 rpm without the optional Corvette exhaust and is SAE certified."

 

450 bhp or 450 whp? Both can be achieved with any of those engines. LS1 = 5.7L 365 HP, LS2 = 6.0L 400 hp, LS3 = 6.2L 430 hp.