What if I have a 96 lt1 fb what would I need to do for the impala lt1 swap and is it less hp?It will swap, but not easily. I assume you are talking about the LT1 V8 from the 94-96 Caprice/Impala SS. That is the same as the LT1 engine used in the 93-97 V8 Firebirds and Camaros, except it has cast iron heads instead of aluminum heads, lower compression ratio, smaller cam and lower HP rating. To put any LT1 in a 93-97 V6 car, you need the complete K-member (lower engine support cradle) from a 93-97 V8 Firebird or Camaro. Then you need a transmission. Then you need a 1-piece driveshaft. Then if you don't have the Y87 option with the limited slip differential and rear disc brakes, you will need the rear axle assembly form a V8 car. Also will need heavier front springs, with the added wieght of the V8 engine and the heavy cast iron heads on the Impala LT1. And you will need a PCM (computer) from a 94-97 V8 Firebird or Camaro, and a complete engine/PCM wiring harness. And it's not likely the oil pan will fit. Need one from an F-Body LT1. Exhaust manifold will probably not fit. Need those from the F-Body LT1 as well.
Now you have an Impala LT1, and the front accessory mount will not match the engine compartment of the V6 F-Body (Firebird/Camaro). So you would need a front accessory mount from an F-Body LT1, and all the accessories that don't interface with the corresponding Impala parts. May need a different PS pump, alternator, AC compressor, serpentine belt and idler.
At this point if you aren't discouraged, go for it. But it would be an awful lot easier to start with the LT1 from an F-Body. Or just buy a V8 car.