Did you try the
The C64 port took a long time because of the reduced number of page zero registers available. The biggest problem was that location 0 and 1 were used for the parallel bus port, and there were lots of places where we assumed the CAR of NIL was NIL but instead it was random dat. I had a kernel ROM listing to help with the register usage, and later a 6510 Andy Finkel had fabbed for me to use with a logic analyzer to disassemble and set breakpoints on memory access for the 0 problem.
I never got the interrupts right for doing setspeed with the sprites... sorry about that.