I persuaded them tighter with a hammer and vise. Not quite as clean or even as I'd have liked, but I'm not at the shop much currently. I wound up getting a bit eager with the vise on the second one and pinched it too tight to get the heel in. Had to hold the bottom together and whack the corners back outwards. Fits alright now, I'll probably even it out nicely in the future when I feel patient and fiddly. Pictures to follow tomorrow.
Your conversion looks good. I like the bail holder, you make it yourself?
Ever put something under the plate around the inserts to mitigate binding suck? I bought some neoprene washers, but they're too thick. Have to thin them out some and try again.