a904 and carb help!

Hello! I am looking for some advice on my 340ci Barracuda. A little backstory, this was my first car back in 2003, I drove it for several years and then parked it for 7 years without running it or anything. Just recently a buddy and attempted to revive it, draining the gas, pulling the plugs and dropping some oil in and hand cranking a few times. New oil and coolant etc. and she eventually fired up. It was working fine until the trans (a904) decided it did not want to come out of 1st gear. I have a column shifter and it would manually shift from park to reverse to neutral but any of the actual forward gears would not work. The car would drive but would never come out of first. Also the carb was not touched so that is going to need a rebuild or be replaced.
Is it worth taking it in somewhere to rebuild the trans? We purchased it from a junk yard years ago for $100. Or do I try to find a used one somewhere and just bolt that up.
Also, as for fuel delivery, I am thinking of just purchasing a new carb, any recommendations? The kickdown I have on there currently was fabbed up by my dad using household items so a carb/kickdown set up recommendation would be great! Or, going EFI? Any recommendations?

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