A large value - 50,000 uF - compared to a smaller one - 20,000 uF - may make the lowest setting too high for thin metal.
So a bank of lower uF caps would be better than one single bigger uF value?
Without trying it, it would be hard to predict exactly what the effect of adding 5,000 or 10,000 or 50,000uF of capacitors will be, and whether it will be helpful in your usage of the welder.
With capacitors in parallel, the total effective value is the sum of the individual sizes. If you buy one or a few smaller caps, e.g. 5,000uF, you can start low and keep adding, but if you can get that 47,000uF/50v for a decent price, then give it a try. That 50v DC rating is on the limit - my Sureweld Monomig 140 has an open-circuit voltage of 43v on the highest setting. You can check your DC volts from the torch tip to the earth clamp at the highest power setting.
For this type of application, the best capacitors are those called "Computer Grade", or "Low ESR" ( equivalent series resistance ), or "High Ripple Current", and with large screw terminals, rather than solder or push-on tags.
This is the thread that discusses the possible advantages of having multiple smaller capacitors:
https://www.mig-welding.co.uk/forum/threads/180-capacitor-swapout.63068/