First of all.. Yes you can use a Vortech 5.3 motor and some even do the whole LSX swap into their cars and trucks for more power. Hassle... Well it depends how mechanically inclined you are and if you're also willing to pay for not just the engine and trans, more importantly, the labor, parts costs associated with the swap etc. The 5.7 motor is a great motor to begin with. Hope this helps.
You hassle will be with the electronics and engine wiring.
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