Be careful with drifting that sight, it really does not take much.
A 8 pound sledge is probably overkill to drift the sight the amount needed and a 3 pounder could be used if handled judiciously . . .
That said . . .
This will allow you to calculate the amount of movement needed.
https://www.realguns.com/calculators...djustment.html
As I remember it took 0.003 front sight movement to move the impact about that much at 50 yds.
I made a Bubba rig using a C-Clamp and a couple of pieces of 3/8 square bar so I could estimate the amount the sight moved by using the thread pitch and amount turned. Does not look like much, but I hit it on the first try so it can be done with rudimentary "tools".