To get files into a 4.3BSD SIMH system the easiest way is with a Python script that blockifies the file by outputting a 32 bits length (say 0x400), then that many bytes, then the length again, and repeat for next block until done. There is also a Perl version floating around which is popular for canned SIMH scripts/packages. Then you mount this file on tm0 (if I recall) in SIMH and then in the emulated system it appears at /dev/mt0. I normally use tar in conjunction but it's not necessary (note star is a highly compatible tar implementation, I think it is by Joerg from this list, although I use actual 4.3BSD tar compiled for Linux and I think gnu tar also works mostly). I can send the details later, I am using phone atm.
Nick