Seems to me you pretty well know what you are doing and I am sure people far more competent than me will give expert advice. Your comment about interference when the latch rod enters the trigger block is interesting ... does this suggest the latch rod is not running true? If so, can it be 'centralised'? I remember a comment by UK Neil in one of his stripdowns that he came across an out of true latch rod and corrected it (not on a 77/97 I think) by mounting the piston in a lathe chuck and tapping the rod to get it right. I have never seen an out of true rod that catches the trigger block.
Personally I turn up delrin guides and top hats and use steel slip washers when needed for the spring end faces. I never bother with threading guides to secure them to the trigger block ... but everyone to their own ...
Interesting comment on bearings ... what sort / size / where from. (the bay reference?). I have seen various comments suggesting needle roller bearing are not worth it / not up to the pressures involved etc. But I have no personal experience of them.
Cheers, Phil