the blocks & heads are all pretty interchangeable, however in canada & most of the US it's illegal to put in an engine older than the car. you might want to check your local laws. even the 1970's cars came with fuel injection, it was only some of the older base models (read low power cars) that cheaped out w/ carbs. if you wanted to upgrade the fuel system, i would get a k-jet equipped car & swap in the turbo k-jet system. k-jet is the cis or mechanical fuel injection system, you can spot it by the rubber hoses leading to the injectors vs. a steel tube rail.
keep in mind that downgrading to a carb would require lots of extras like a new intake manifold, wiring, etc. and multiple carbs can require a lot of maintenance.
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-- '82 245GL, B23E, K-cam, under restoration, 350k km --