There would be a few questions for you to ask yourself Rolf.
Firstly, what do you what to do with the rifle, what game do you intend to take?
Will it be long range work from a vantage point or stalking game?
What projectiles do you intend to use & will the existing twist be okay to do so. 1:14 is slower than the normal 1:12 so only lighter projectile could really be used
As to why old mate got rid of his rig in 150-200 rounds may be another call to ask, but I'd reckon he was going for every bit of speed he could & use them like a grenade inside a fox; a lot of hunters down South used to do the same thing until the fur market dried up due to all the Greenies!
The last thing I'd like to see is the grouping on this rifle or give it a go yourself if possible!
If it all stacks up your way & its the rifle for you mate then getting it docked & rechambered will still be another issue, but it'll be what you want!
Got to have the right spanner for the right nut hey!
All the best for 2022 mate, hope you have a win.
Cheers
93x64mm