I made some progress on this front :
– I bought a prestolite 66021151M at £110 from Britain, it incorporates a basic regulator, form factor is almost the same though the “foot” (the part used for the main axis) is lowered from 3″ to 2″ . Some piece of still will do the trick
– Later I shall install an external 3-phases regulator (bulk-boost-float), very likely using Sterling products, either the AR12V (£90 but quite cumbersome to install) or the AtoB model (some £300, trivial to insert between regulator and battery banks)
I’ll gladly read any comments about this project.