Thanks @Capsat.
As mentioned the governor tooth broke leading to a wild engine revving to red line. I am not yet well versed on how the injection pump mechanics work but I assume it is relevant because the governor limits the distribution of fuel amount tot he engine.
I have not yet seen an after effects of such but I don't think it will kill and engine right away considering it had a good amount of oil when it went wild, and it didn't blow a connecting rod as you never mentioned it.
There is one thing though I had in mind when you said that the engine can only do 80-90kph at the moment. After the injection pump has been calibrated and done, I am assuming the Main Fuel Load was lowered or adjusted that it had limited the amount of fuel given throughout the rev range.
That main fuel screw controls the amount of fuel given by the IP throughout the rev range, when you turn the bolt out it gives less fuel, turn it in and it gives more fuel.
I have a few questions though:
Is the engine sound like it used to be before the trouble? or is it more silent now? I asked because timing affects engine rattle, the more advanced the injection pump body the louder the rattle, delay the injection pump body and it becomes a very silent diesel engine but low on power.
Does it blow a puff of black smoke now after the fix? Or does it NOT show any smoke at all?
I asked because a very lean mix will show No smoke at all and will limit your engine power thus slowing your acceleration and top speed.
Does the engine start normally Like it used to? If it does then timing is of no issue.
If al of the rebuild was done immaculatley by the boolk/manual, then I am assuming fuel limitation is the issue to why your engine became slow.