At that point I'd just make a pivoting mount for the petrol power head. I've not come across any electric chainsaws that would compete with drive equivalent to a 562XP (5.5hp). The whole point is that it's got enough guts to run a 20"+ bar reasonably well. A 5 or 6hp electric motor becomes quite a substantial thing.
Also feels a bit more elegant so at the moment this is vapour build, the cherry picker hydraulic motor is just sitting there hence the query. As @Rannsachair says proper processing head motors are big bucks so it may not happen that way.
Although continuing to explore the hydraulic motor option does anyone know what speed cylinder mowers (the big triple Toro style ones) spin at?
Another common part seems to be a Parker 6405W but I can't find any details on that at all.
From what I can see they look direct drive and there are a few motors on ebay for not a huge amount.
As removed from a running, driving, year 2001 Hayter T424, 5 gang cylinder mower with Kubota V2203 4 cylinder engine, showing 1768hrs. Evidence of any tampering will invalidate any warranty claim. Good USED Condition.
www.ebay.co.uk
Another option is if there's a flail hedge cutter motor going cheap somewhere but u haven't come across one yet.