They're not lifters as such on this just knuckles with restriction and is central on the rocker so the roller follows the cam and the other end pushes the valve and the middle just gets a lube of oil and dampens any slack.
I think I've sorted it now, I'm partly embarrassed but will take it as it is. I spent 40 mins lying on the ground locating the slot for the crank, and having done that it also corresponds with the 2.5 teeth anticlockwise from 12 o clock. But it means that the crank was 1 tooth out.
So, as much as I checked it before and it running perfectly I guess when oil pressure and engine temperature was achieved then going up the hill and loading the engine, that then gave enough fouling on the valves to damage a rocker. I don't know if 1 snapped and the bit bounced about and damaged the others or they all went.
I've done a few of these and not really had a problem with the crank slot, so I must have just got sloppy and assumed that I had the right slot and that only the inlet cam was out originally.
Which won't happen again.
Fortunately I have only wasted some time and some sealant on the timing cover. That's assuming there's no damage to the case or anything but I'll find out when I run it up. Might still get paid.
Cheers for the help guys it's always good to get ideas and tips no matter how much we think we know, standing back from it and having a think usually helps loads.