Trying to think from memory that If I had to attempt this I'd probably try to go from underneath.
I'd probably move the engine forward as well to allow better access.
But I am sure the more sensible approach is probably from the top. I know its only a handful of bolts to get it out but its squeezing it past everything and the wiring that'll get in the way. You might need to remove the offside drive shaft in order to do so as well as move the engine forward.
You'll definetly need to remove part of the exhaust flexi and the bottom engine amount.
Alfa 166 2.0 Twinnie - LPG and a few trick performance parts