84 injection switch to carb

Would like to go old school with my 84 and switch to a carb. what are the downfalls of this. Will it even work.  

It'll work just fine.  The only downfall might be a slight decrease in fuel mileage performance, but you'll probably see an increase in horsepower & torque.  The major upside will be reliability, as the cross fire injection tends to be finicky.  There are some people that post here that have great luck with the cross-fire though.

But back to the point, as for going to a carb, you'll need to get a new intake manifold, a carb, and the proper fuel lines.  A standard single plane manifold should fit under the stock '84 hood, but if you want the increased performance of a dual-plane or Edelbrock Performer RPM intake, you'll probably need to see about getting either a new hood or a bulge added to your current hood for clearance.  As far as your carb choices go, the Edelbrock Q-Jets are usually pretty good for fuel economy, but poor on performance compared to a Holley, which isn't very good on economy.  A Demon is the best of both worlds, however, you'll be paying at least double the cost for a demon than you would for an edelbrock or holley carb.  It really depends on your budget and your intended goal for what you go with.  Honestly, if your engine is otherwise stock, you'd probably get along just fine with a standard single-plane intake & a Edelbrock Q-jet.  If you were going to swap out your heads for something more powerful, or get the engine rebuilt along with new or ported heads, then you could probably benefit from a bigger intake and more powerful carb, but then you'll also be looking at hood modification costs too.