Hello again,
The Mule will be an Alnico IV, and by default the Stormy Monday ships with an Alnico II unless otherwise requested.
I would recommend an Alnico IV for your purposes, otherwise the neck (whilst being clear) - might not have the same 'focus' as your Mule under gain, especially as the neck pickup is under the strings at a point where they oscillate wider and are less 'tight' anyway.
The main difference you will find in the SM as compared to the Mule (even though they have close impedance readings) - is that the Mule has a slight midrange 'hump' - whereas I find the SM has equal emphasis right across the frequency range. The Bass on the SM is also clear, but somehow looser sounding than the Mule, especially with an Alnico II magnet.
If in doubt do ask Tim or his team before ordering - as Tim put me on the right path with which P/U to put in which guitar for my style/ purposes.
These are just my observations based on trying Alnico II SMs and then Alnico IV Mules in the same guitar (a Les Paul Standard). Having now heard my SMs in my S.G. and Les paul, I would say they work well in both, but the Mule better in the heavier mahogany body and the SM in the lighter mahogany body. A 'V' is about in the middle as far as weight is concerned.
Happy hunting !
Regards,
Derek.