For example, running the BeebFPGA core with external Tube support, but with the Spec Next Pi Accelerator present instead of PiTubeDirect. Also, as I don;'t actually own a Spec Next, and have to borrow ...
This looks very impressive. I've been playing with the BBC Micro Core on the DE10-nano/MISTer platform which has limitations currently. Your BBC FPGA is considerably ahead. Have you by any chance ...