360 engine vibration

Compression all good 150 PSI across all cylinders. the damper looks relatively new.

Oil and filters changed twice, cant really go on a long run as car not yet UK road legal, so at present only had it ticking over and rev up to about 2000 rprm, maybe a blip to 4k now and again. I might drop the oil again or try the additive and oil flush. A lifter problem would fit the bill for the frequency of the vibration. It feels like its missing on a cylinder and lumpy. The front pulleys ( v belt ) have a slight wobbly but the harmonic balancer is steady, so I will strip this off , check part number and post a picture and eliminate that wobble.
If I take the plugs out, rocker covers off crank over and measure lift on all valves that might show up a stuck lifter?