Congrats on your success. A lot of the A bodies are notorious for bad bulkhead connections, especially the one that carries the larger gauge wire to the ammeter (these in some cases are melted if the small alternator capacity is exceeded). If it is, it is a good idea to bypass the ammeter and there are lots of good instructions for doing this on the FABO site (For A Bodies Only). Actually there are lots of great tips for many things on this site if you have not already checked it out. ABC's of soldering. First you have to make sure you are using the correct solder for electrical wires, if you are you won't need to use flux. If the wrong type of flux is used it will cause you issues and make a poor connection. Make sure the wires/connectors are clean, if not then clean with alcohol or brake cleaner. If splicing wires, first slide a piece of heat shrink tubing over one of the wires to be spiced, then with your wires prepped (for stranded wire ideally you would skin equal amounts from each wire and intertwine them by pushing them into each other and then twisting to tighten the splice and if solid wires you would probably just twist together tightly and fold back over one side). If attaching a wire to a connector (if it has no hole to put the wire through) skin enough wire to wrap around the terminal and twist). Tin the iron by cleaning the tip with a brush as it is heating to get off any previous solder, then you want to melt some solder onto the tip and give it a brush. To solder your connection you want to put the heat under the target wires/terminal and hold as you place the solder on top of the connection - if the solder isn't flowing within a few seconds you can place the solder onto the tip of the iron where it meets the target to get it melting and flowing then move it up through the target wires/terminal to ensure you have good coverage. After cooling you can slide your heat shrink over the splice and either use the shaft of the iron to move along the shrink until it does shrink or you can use a match or lighter under it, moving it quickly along to shrink the tubing. Obviously if you have no heat shrink you can tape a splice or paint on some liquid insulating rubber to prevent the connection from deteriorating.
