BTW, does anyone have some pointers to where one can find an oldish in-order Cortex-A core (like A53) in verilog RTL form? I know ARM must give this out to companies that implement ARM based SoCs for eg. purpose of validation on FPGA.

So far I've only found various M cores online. It would be fun to have something to experiment with on a cheapish FPGA like Kintex XC7-K480T, that may have enough resources for some in-order A core, and can be had for $50 or so.