Thanks PurpleBeeper,

Good to hear any lifter will work on my street motor and that the magnet method might work!! I am really reluctant to remove the intake/cam etc as I was hoping to get at least another year on this motor before a major rebuild. I had the heads rebuilt 18 months ago and the cam looked ok from a quick visual and has always run quiet. In hindsight probably should have replaced everything then!!!
I do know the chain was replaced at about 150k. The engine does burn a bit of oil but generally runs very well. Attached picture of cam lifter area.