Pesky, while the specs look close, the 5687 is not pin compatible with tbe 6H30
I‘m pretty sure you can get adapters though. I know there were ones that let you use 6N6Ps in 5687 apps. If not, it‘s pretty easy to make yr own. I never let pinouts stand in the way of subbing - it‘s too limiting: if it works and I‘m happy I just re-wire the socket. Easy.