Felix the standard offset of my original Yokes I make 36mm which results in the standard trail figures of either 91mm or 97mm depending on which rake setting is used.

As I have a Lengthened swingarm (standard one extended) which Ray Stringer had done when he was racing a much modified 916SP Devimead Ducati along side team mate Steve Hislop on a full Factory Corsa in 1995, I thought I would go with his settings.

From what I can make out Felix your bike on 23.5 degrees with 28mm offset would be runing longer than standard trail of 99mm which is quite a common figure for the Factory race bikes.

So the answer to the question --- Why increase trail by reducing offset ?
Answer--- because its what appears to work on Ducatis

which is one reason I'm against using the standard 23.5 degree setting with standard offset yokes

He fabricated a different different headstock spindle that allowed him to use the standard SP yokes fitted with eccentrics to achieve a yoke offset of 32mm identical to the 1994 Factory Corsas. Hizzys 95 Corsa had a offset of 30mm

Foggy's 955 from 1995 ran 100mm of trail and a head angle of 24.5 degrees along with the longer Corsa swingarm, used 17" wheels and had a weight bias of 51.5% Fr and 48.5% rear weighing 153kgs with No fuel tank but with oil & water. Wheelbase was given as 1428mm.

Had this happen to me a couple of times, and have learnt from it.
Once on an old TZR250 and the chain was old, and also on a ZZR600 where the previous pillock fitted the sping clip the wrong way round and it let go after 2 months +
Scares me to death now.
I have just gone back to a 525 on my NC30 and also on my 916
I bought brand new chains from new 999's as they were being replaced with gold racing 520 chains. The original stuff doesnt look pretty but is damn strong and weighs a ton (hence why they get junked)
And to be honest i am sure a well maintained OE equipment 525 chain is more than up to the job of hauling an old 916bp about with ease - hell i reckon it would pull the QE2