Adjustable lifters are not mandatory, just a bit of a minefield it seems.
There are problems with soft ones (probably not your problem) but there are also problems with them not holding a setting (the screws move in the lifter.- could be your problem?)
If she won't start from hot, then I would go to the coil. This might be your cause of the erratic spark? I say this because f.h. coils give a lot of trouble, even NOS ones. Of course there are plenty of other things to make her hard to start from hot. The coil is just a very likely one.
It sounds like the carrier could benefit from someone going carefully through a tune up.(Your problems may well resolve them selves with valve clearance.
Now that you mention it, it makes sense that she doesn't idle down to a nice smooth 450 rpm