Well, I bought the largest animal vaccination syringe at Tractor Supply co, $1.89 (60cc), plust another $1.10 for the needle tip. (Veterinary use only!)
I had a piece of plexi-glas, cut it to size and drilled a fill hole in it, slight gease around the edge of the chamber, placed the plexi-glas over it, and filled her up. I did it on the head I knew the size of first, and it came out almost exactly right at 65cc (the head is 64cc).
So it works, the only trouble I had, espcially on my old heads, because the volume is greater than 60cc, I oculdn't refill the thing fast enough because some fluid was slowing leaking out through the valves while I was trying to refill the syringe, but a little grease on those valves took care of that.
If they had an 80 or 70cc syringe, that would be better, but 60cc was the largest they had. (that's alot of dope!)