I got to see those pedals, Cliff Halsey, a Shimano Pro of the day made a pair for himself as well.
They were pretty crude but worked.
Basically a alloy block bored out to accept Campagnolo races and axles that were shortened for more pedal clearance, alloy angles were used to tie the body to the shoe to keep the distance from the foot to the pedal axle as small as possible, no dustcaps, no grease. The alloy angles kept the base of the shoe stiff as well.
I doubt the Cinelli M71 would have been considered.
The downside was that the shoes did not last long as there was no strap to take the load away from the shoe upper from the sole connection.
Prior to the "Europeans" coming over here for the Grand Prix of the United States races in the mid '70's at Encino, the ABL of A officials always gave grief to those who did not wear socks, & they had to be white.
John Jorgensen
Palos Verdes Ca