I've never used PostHouse before, just saw their services. I have spent lots of time trying to clean up poor-quality telecine transfers and poor-quality 35mm slide scans. If at all possible it's worth having them done professionally with restoration equipment designed for that.
Here is a transfer done by "Transfer Lab" which they claim is good but IMO it's very poor quality. The dust & scratches worse than original and the sharpening is artificial. This is an example of what you *don't* want, whether in-house or out-sourced: