Typically..MOST...not all ...vintage Acoustic heads..power..PA will handle down to 2 ohms with no issues.
On that site, see 'dznr's ' posts, as he is the guy who DESIGNED the vintage ACC products.
Also there is an Acoustic Club here, on TB....but the REAL DEAL is the'unofficial' site.
'Unofficial' is used due to some proprietary issues. Not nearly as much traffic on that site as on T B generally,but not every TB-er is an 'Acoustician".
To me, it's a coin toss between Vintage Acoustic and Vintage Sunn...then there's all the rest.