TBI or throttle body injection, would probably be your only good option. There are a few systems out there for earlier Jeep 258's so that would most likely be the easiest and most adaptable option.
Anything GM I can think of in an inline was a 4 cylinder 2.5. The rest were all either 2bbl throttle bodies on the V6's and V8's, or port injection, which would be a lot more work to adapt.
The only part that would be a little tricky would be to have an adapter made to mount the throttle body to the stock manifold. Other than that, the rest should be fairly straightforward.
New fuel and return line, electric pump, 24-12V converter, wiring harness, computer, sensors, and programming software are all considerations in these jobs.
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