Get a PC-9821 model (there are like hundreds, it's hard to just say "get this particular one", etc - they'll all work), not a PC-9801 (ancient) one. I recommend at least a 200MHz machine.
PC-9821 machines will run a lot of PC-9801 software, except for some really old (like, early to mid 80's) stuff, which I consider a blessing, rather than something bad.
As long as you get a stationary machine, it'll have c-buses. Not to worry.
Look forward to the shipping costs.