Pinto automatic

[Montenegro]

Hello,

I'm owner of 1984. mk2 Transit camper with 2.0 pinto engine and automatic gearbox. I'm not content with performances of it - high petrol consume, and low power especially when I drive it in mountines.
I ponder about changing engine, and I readed on this forum that machine 2.5 DI is the best solution,
and I'm asking somebody of you - is it possibile to do it if I don't want changing my automatic gearbox?