Happy new year!
Interesting thought - I don't think its a simple changeover by any means - it would be a little bit like changing an old petrol engine from carbs to a modern FI system.
If you could get it to work the advantages you would see from the swap will be less noise (the noisy part of an old Diesel engine is the mechanical fuel pump), less smoke under load and will use less fuel. You probably wouldn't see more power though.
If you want more power from a Diesel you have to make a bigger bang - power = size of bang x number of bangs (BHP = (torque (lb/ft) * rpm) / 5252 - I think). You can't make more bangs as Diesel doesn't burn as fast as petrol - hence the lower max engine speeds.
To make a bigger bang you need to burn more fuel. You could adjust the injection pump to do this probably but you will see more smoke and potentially it may make no difference to the performance at all. You also need more air as well, so to really make a difference you will need to go with a turbo.
If you have access to a complete replacement engine then that would probably be the least painful route to turbo boosted happiness.
