Please first explain how your engine has BOTH fuel injectors and a carburetor. My experience is that there is one or the other.
For all of the work you've done, (which may have been needed anyway) have you checked the engine timing, with a timing light? You will need a tachometer to tell engine RPM also. A do-it-yourself book like Haynes will give you the procedure and the specifications you need to set the engine up properly. This is the next step, take it and I believe that your car will run like a top.
Some refer to the throttle body fuel injection that you have to a carburetor.Can you tell us in detail the driveability problems you are having with the 305 engine at this time?By doing so someone may be able to solve the problem.Check all vacuum hoses for leaks and correct.
It could be a bad lifter,worn cam shaft,valve improperly adjusted.there are several things that could cause it to run poorly.Misadjusted carb,take it to a mechanic and have them look at it,at this point you can do alot more harm than good.
Don't replace parts that aren't broken or wornout, it's a waste of time and money. Compression, fuel & spark are all she needs to run right. You may need a manual to help you identify all the components.