acvirus.cpp will eventually need the 80C515 and 80C535, which are both 8052s with more I/O ports and peripherals.

That's not too different in concept (adding ports 4 and 5 and a compare/capture unit or two) from Intel's 80C51GB, which I recently identified scm_500 as. There are a countless number of further-enhanced versions of the 80C51 and 80C52, but the only ones that I think might be relevant for the exerciser proposed here are those such as the DS80C320 which have shorter machine cycles of 4 clocks each rather than 12. (There's also the AXC-51 type found in the Monon Color, but that barely even qualifies as a 8051 clone due to having a 16-bit ALU, many new instructions and 100% different on-chip peripherals.)