That looks amazing!!
Cool to know about weird 8track devices, will look out for one ha.
I have just one play/record 8-track deck at the moment, alas it can’t tape monitor (don’t know if any normal 8-track recorder can) so can’t be used for tape delay. I had a quadraphonic recorder (!!) at some point but it never worked and I had to get rid of it during a move years ago 
Was just having a mess around with 8 track loops vs eurorack, promising but i need to sort something out to get good levels into the recorder… weirdly rather than being too loud as expected the eurorack output comes out too quiet :-/