MK3 AGG vs MK1 DX Engine Torque

I currently have a Kjet DX engine in my VW T25 campervan. It runs OK but I have to give it some lower gear high revs to get it up steep hills and at 80mph on a motorway. Part of this is the 4 speed gearbox and the 215 75 15R wheels.

I am in the process of having a low mileage AGG prepared and will be installing it in August, I just wondered what sort of differences I can expect.

Is there more torque low down in the rev range? Will it allow to stay in gear slightly longer? How do the 2 engines compare?

Thanks