All my LF lenses are old too. I trust the times to be approximate, and usually stick with times I can check by ear. They also need manual cocking.
Yet I have had no problem at all using the LesMcLean Mulitexposure technique, with 16 exposures each 1/4 second the result was even better than I hoped. Use a sturdy tripod, a heavy camera, and clamp everything down tight.
This is one of the few situations where an old Linhof Technika III 5x7" is better than a brand new exotic-wood-and-titanium camera!