EFI

"71 LM318 What is the feasibility/possibility of installing EFI?

feasible...Yes; cost effective....probably not....

pretty much will be determined by your budget.....

It's dead simple. Parts very cheap and plentiful. Literally dozens of options from fully kitted boxed systems to junkyard pulls. You can do it for a hundred bucks or several thousand.
I recommend a Rochester TBI type system. You'll need an adapter plate for the intake manifold, and the fuel system plumbed for return line to the tank. The computer you can pull out of any number of GM vehicles from the late 1990s thu the mid 2000s, or find ready-to-run units from one of the many who offer them. Just google TBI and you'll find hours and hours of reading, videos, websites devoted to this type of system. Simple, robust cheap.

How about adjusting the idle...??? I learned the hard way the only way to engaged my
drive is at a few hundred RPM

Jack