How much do you need to sync? If its a huge project, I suggest picking up Plural Eyes. Its about $150 and will analyze the audio from the camera scratch track and sync it with the properly recorded audio.
Otherwise you can throw your footage onto a timeline, throw your audio on a second track next to the camera audio, expand and zoom into the timeline and line the waveforms up manually. In the upper right of the timeline panel there is a little settings icon, you can switch the timecode to show audio units and this will make the re-aligning of audio more exact. Once it’s aligned, unlink the camera from the scratch track and link it to the recorded audio. Unfortunately Premiere can not make subclips if video and audio are linked from two different sources… so you have to keep this “sync timeline” around for grabbing footage from.
The DSLR workflow… sucks. Timecode makes life so much easier. It’s something I’m very familiar with as I’m pretty sure I was the first to stick a 5D on a technocrane and on an ultimate arm. They’re lovely for what they are, but limited in so many little weird ways.