Lovely bike. You're probably better waiting out for better selling times. Could be years away but as others intimate here you will not anywhere near your current price.
In the UK it feels like the bias is towards larger tyre clearances and mudguard and rack fixings. Pure race machinery with x25 or x28 max clearance is seen as a bit limiting now with the trend for wider rubber.
Fair comment @Nothin-fancy . I just sold a totally original Raleigh Quadra for £110 BIN and had it on eBay for 2 months before I got a bite. I was very close to just taking it apart and putting it in my loft, prepared to ride out the current 'prices in the crapper' phase and wait for better...
I personally love that era 105 (1050). It will last forever and has the reassuring THLACK missing on weedy chain setups. Rest of the bike is lovely too.
After some hiatus things are moving again. This is the weather to sort the frame out.
The stainless headset cups were a total sod to get out. A mixture of creating grooves in the material with a Dremel and then levering out enough to get a screwdriver sized gap below where the cup meets the...
Thread 'Large Austro Daimler SL - Ilkeston - £40' https://www.retrobike.co.uk/threads/large-austro-daimler-sl-ilkeston-£40.494290/
That struggled to sell on the bay.
This one is nicer and in a more popular size...but a monkey is crazy talk.
As an aside I ran dia.compe(Gran Comp) 610s which are CNC manufactured on my Mercian winter bike and wasn't impressed at all. The cheaper forged alloy dia compe DC750.centre pulls are far better even on stock pads. On kool stops they are really quite decent and certainly way more powerful than...
What year Mistral? I would have thought anything before the 80s would have been on 27x. If it's got centre pull brakes then you're usually free to use either size given the range of adjustment available.
Lovely looking bike. I wonder why David Hinds did not try and put more graphical distance between himself and Dave Hinde. He has used the same losenge panel graphic as Hinde.
As @bulgie has been kind enough to offer we download all we can it may be a good time to look at something like HTTrack - that allows you to download full sites.
https://www.httrack.com/
Then with a local copy of velobase you need not sweat if the site takes a breather.