Even the 41 could run from Shrewsbury with a similar dead mileage
Are you sure?
The 41 works with 3 buses. Of which
1 starts in Whitchurch and finishes in Chester
1 starts in Tattenhall and finishes in Tattenhall
1 starts in Chester and finishes in No Mans Heath
Bar the 1 bus which starts in Whitchurch, every single dead run is 10+ miles extra dead running each way from Shrewsbury the 41 start/end point, versus Crewe to 41 start/end point.
If Hotspur ever won the 511 they could probably interwork
Sure. If you want a stupidly unreliable bus, or very inefficient one. The 41 serves chester which has unpredictable heavy traffic. And the 41 timetable is built somewhat around some school transportation. The 511 serving Shrewsbury which somehow has even worse, unpredictable traffic. Especially from Harlescott into Shrewsbury near the train station.
You'd be completely and utterly barmy to interwork the two services. That's before you look as the fact 1 driver couldn't do a round trip within the 5h30 stint, so you would have to timetable and guarantee a 30 minute break in Chester (if running from the Shrewsbury end), which while doable, makes things a lot less flexible and means the smallest thing goes wrong and you end up delaying the rest of the trips.