@aminkus my friend,
@375Fox is 99% accurate on all subjects discussed on this site

You should accept his wisdom.
Further, our
@michael458 designed the Cutting Edge Bullets' Safari Solid and Safari Raptor bullets. Their solid's with its 67% meplat underwent extensive testing for both depth and straight line penetration. Michael posted many of his test results on this forum. Searching for and studing his posts will provide a crash course in ballistics / bullet performance. There may be equals to CEB Safari Solids, but I seriously doubt there is anything better.
If you were loading for a more logistically available .416 or .458 bore, I'd send you Safari Solids to try. But since you need the .423 bore, here are your best choices,
View attachment 798657
"
.423 diameter 400 grain Safari Solid™ hunting bullet designed for
404 Jeffery Rifles. Design incorporates
3 + 1 band configuration for reduced barrel strain. It has the
67% Meplat BBW#13™ nose profile which has proven to give the deepest penetration of any bullet tested to date."
or their .423 diameter 350 grain Safari Solid
View attachment 798658