Things have changed. Used to be you could pull an engine out of a junker and drop it into something cool and it would run. Not any more. This Hot Rod magazine story shows how things have changed. The "junk yard jewel", a 4.6 liter Ford V8, won't run as it come out of the junkyard. The electronic boxes that make the fuel injection run don't come with the engine and the electrical harness to the injectors is toast.
Solution. Simple. Go with a carburetor. OK so far, except the carb needs a new Edelbrock intake manifold for nearly $600. The whole damn engine only cost $400. So before they can even crank it over, the $400 engine becomes a $1000 engine. I can remember replacing the entire engine in a hobby stock racer for $50 total. Speed costs, how fast do you want to go?
And then, Hor Rod magazine had access to a dyno. Us shade tree mechanics used to judge improvements in engine power by the seat of the pants, or quarter mile times, or looking at manifold vacuum. Dyno was a luxury far beyond our pocket books.
I shouldn't carp. Following this article you can produce a very strong engine from readily available parts and the whole project is less than $3000. They pushed the stock Ford mill from 200 and a skosh horsepower to nearly 400 horse and it's still driveable in the street.