Just one thought there RBrit....... As one who has removed, refitted, reamed etc etc many, many of these, here's a question. If the taper pins on yours didn't align (and that's 100% of your attempts.....) what makes you think that the foresight block/eliminator will just align using the taper pins if you don't align the flash eliminator first? In MIGHT of course, but if it doesn't, by just a gnats knacker or so, then the foresight block will be off centre.

This is OK if you can then align the foresight block by slightly breeching up tighter or slacking back a tad. But I would align first THEN ream out THEN fit new pins. Just my thoughts.........