That is a very attractive rifle and should bring you a lot of pleasure.

If a shooter of modern .405 WCF could add a comment on peak chamber pressure?

When I began loading my Miroku/Winchester 1895 TD .405 WCF with the then new North Fork bullets, two things happened:
1. My older brother(a chemist and gun nut) introduced me to VV N133 powder, he told me of how it generally had 10,000 -12,000 lower pressure peak than most powders.
2. A very experienced loader and shooter with his own pressure testing equipment told me the same thing as my brother. He also mentored me on loading the NF bullets for best performance and suggested that I buy pressure testing equipment if I planned to push the upper limits on any cartridge.
3. I bought Pressure Test II and it really opened my eyes and helped me to safely explore some upper limit loads because N133 made those loads normal peak pressures, not upper limits.

One example was 400 a grain .405 load at 2100 fps which ran a peak pressure of 48,000 PSI with a good ball powder. It worked and I killed my Cape buff with it.
I then loaded the same bullet to the same velocity with N133 and the peak pressure was well below 40,000 PSI. I loaded this load for my .405 double rifle and it likes it.
A fellow shooter/hunter asked my advice on loading his .405 for Africa and I told him about N133. At last report he had the 400 grain Woodleigh up to 2157 fps and was heading for 2200.

IMHO, N133 should be considered for use in any rifle where a high peak pressure could be troublesome if not traumatic.

Please let us all know how your Lancaster works out for you.