The syncing is always challenging, did you try zooming in on the waveforms and matching them visually?
Also, checkout http://www.izotope.com – their Nectar product – and http://www.bias-inc.com for some great audio tweaking tools. Both offer many presets and can be stand-alone or plug-ins to your NLE. Nectar is on sale for $199 and there is a consumer-grade product for $39 that looks promising. Bias’ offers SoundSoap for $129.00
