Actually you have left me confused and thinking this is a bad idea. If I understand what you are saying is;
1. Electroless Nickel applies evenly but will peel if scratched and will discolor with use.
2. Electo Plate does not apply evenly meaning high and low and no spots.
3. Hard Chrome is durable but has high and low and no spots.
The blue finish on my Uberti 1873’s is in excellent condition. The factory blue does look uneven on the side plates maybe suggesting high and low spots in the steel from not being sanded down properly.
So (#1) Electroless Nickel is out due discoloration with use.
1 and 2 will peel from Hoppe’s #9 or aggressive cleaners. So both are out.
That leaves (#3) Hard Chrome. Will being brushed hide the uneven surface?
Do all of these give unsatisfactory results on long gun with smooth steel? This as compared to bead blasted rough base metal such as on a shotgun.