I forgot it had electric power steering. So that's one less thing to worry about. lol
99% of the time the AC won't turn it, it's because you're low on refrigerant and the low pressure cutout switch is tripped. There's no point in doing any other diagnostics until you get a set of gauges on it and check the charge.
An ER27 is a big EA82 engine, with the same bellhousing. A newer engine will need a bellhousing adapter and redrilled flywheel, unless you run a newer transmission too, which is its own whole set of adaptations.
Pitch stop is the link on top of the engine to the firewall. You have to fab brackets for it for an engine swap.