Here is how events unfolded. The first ‘flow bench’ was in fact my mother's vacuum cleaner. What I did was to mount the head to be tested (an ‘A’ Series head as per Austin/Morris engine) on the block with a means of opening the valves. I then located the suction side of the vacuum cleaner to the bore and sealed the hose so there were no leakages at this point. Next a spark plug with the middle removed and a piece of ¼ diameter copper tube glued in was installed into the spark plug hole and connected up to a manometer made for clear plastic tubing stapled on to a 8 foot long piece of 2 x 4 wood. This was marked out in inches from – 48 inches at the bottom all the way through zero to plus 48 inches at the top. The plastic tubing was looped so that the bottom of the ‘U’ was formed about a foot below the bottom of the 2 x 4. Water with food dye was used to fill the ‘U’ section of the u-tube until it reached the zero mark.
I read about that, I think it was in Hot Car magazine circa 1980! I built my own using an old compressor, the results weren't particularly repeatable.
