Chapter 11 in the PDP-11/70 handbook describes the console operation of the actual 11/70. The fidelity of the PiDP to this is of course a different question; my impression is that 'major' functions are fine, but of course anything related to microcode is not.
Speaking for the 11/70: all of the general registers are mapped to physical addresses, and they're listed in Appendix A (section 4). The two register sets and three stack pointers have different addresses. These are also listed on page 11-4 of the PDP-11/70 handbook:
The General Registers can be examined and deposited using the EXAM and
DEP Switches provided the previous LOAD ADRS operation loaded the
Address Display with a "register address."
17 777 700 Register 0 (Set 0)
17 777 705 Register 5 (Set 0)
17 777 706 Register 6, Kernel Mode
17 777 707 Program Counter
17 777 710 Register 0 (Set 1)
17 777 715 Register 5 (Set 1)
17 777 716 Register 6, Supervisor Mode
17 777 717 Register 6, User Mode
Examining and depositing into General Register Addresses is
independent of the Address Select Switch. It is not possible to be
mapped to a General Register.
For 'bare machine' operation, it's probably convenient to have ADDRESS SELECT on CONS PHYSICAL (and thus addresses are 22 bit physical) and DATA SELECT on DATA PATHS.
By the way, there's a Google group specifically for PiDP-11 questions, in case that's useful. See the 'forum' link from this page.