Putting a 1.6 Zetec SE in my Ginetta - struggling to get the valves shimmed properly when installing uprated camshafts.

Getting inconsistent readings (IE, shim it, turn it over a few times and measure and get 1 reading, turn it over again and get a different reading) I think this is due to worn followers. The cheapest I can find is £8 each for new followers which at 16 off is £128, assuming I get it shimmed correctly first time round.

Anyone have any suggestions of cheaper sources? Can I get the followers surface ground flat? Any hydraulic follower upgrades available?

These are the solid followers with the button machined into the underside to adjust the clearance. Really annoying because you need to remove the cams to change the followers!

Cheers,

Matt