Agreed on Takayanagi's New Direction Unit. The Axis: Another Revolvable Thing set is also stunning; it's from around the same time. The "Mass Projection" track on volume one is sick - I didn't realize that something could take "Echo"-style density as its starting point, and get denser and freer every couple of minutes... mind-melting. Takayanagi's also good on Masahiko Togashi's We Now Create, a rare Japanese Victor session from '69 that was recently reissued. Yoshizawa and Mototeru Takagi (tenor, cornpipe) also make appearances. Apparently that Eclipse session, first on an Iskra LP, was slated to be Takayanagi's ESP debut. Unfortunately ESP didn't have the bread to put it out at the time, and shut down shortly thereafter.
I too have been scratching the surface on some of this material as of late; Abe's the next major project, though I do have a couple of Overhang Party records (Abe/Sabu Toyozumi duo) that are really great.