BHK himself recommended the Tungsram PCC88 (7DJ8 I believe) and that is what I and several others have been using. Nice sounding tube and readily available. I’m sure there are many other options, but I’m happy with the Tungsram
Could you please share the contact details of your valve supplier, “stevenvalve”? I’m looking to roll the tubes in my BHK300s which are now 2 & 1/2 years old. I’ve just ordered some Tungsram PCC88 tubes from the USA (tubemonger.com) for my BHK preamp.