I have quite a few 7 inch reels of standard play quarter inch Zonal 675 tape for sale. It is said to be similar to Ampex 788 and works well on machines biased for Amped 456. Just £5 a reel plus shipping.
I am UK based.
Cheers
Ian
P.S. I also have about 50 Zonal D90 Audio DAT tapes to dispose of if anyone is interested.