4.8, 5.3, 5.7, 6.0, 6.2, 8.1
Some of these are Iron Block/Aluminum Heads, some are Aluminum Block/Aluminum Heads. Complete engines with all accessories, pcm, wiring harness, etc can usually be found for $300-$5000 depending on which engine it is, what is included, etc. (Obviously a Corvette Engine is going to cost a lot more than a truck engine)
In stock form a 5.3 truck engine puts out over 300hp, and many of the older vehicles with LS engine swaps are seeing over 20mpg.
The EFI conversions are easy to do in older vehicles requiring only 6 wires to be ran to the actual vehicle, and there are also affordable carburetor conversions.
These engines bolt up to almost all GM transmissions, including the Hydromatics, but are mated to T-56, 4L80-type modern transmissions, which are also easy to install into older cars.
There are many budget LS swaps out there, with some people spending less than $1000 to convert their SBC-powered vehicle over to a carb or efi LS engine.
I intend to do the conversion in my pickup sometime this year. Using a 5.3 Liter Chevrolet Truck engine, with a Camaro/TransAm/Corvette style intake manifold and oil pan for clearance. Stock truck headers, stock EFI system with reprogrammed PCM and custom made wiring harness. Add a set of motor mount adapters that bolt the engine to stock SBC style mounts and a trans adapter to mate it to the TH350 transmission and I'm done for under $1500 total investment. I can't build an SBC with reliable 300+hp and get 25mpg for anywhere near $1500...the LS swap solves this. Since I drive my old truck every single day, hundred of miles a week... the EFI LS only makes sense.
is a great website for information.