I probably would have suggested something like this
http://www.teleskop-express.de/shop/...ength-3mm.html
or these
http://www.teleskop-express.de/shop/...ss-1-0-mm.html
as it seems to reach focus already it's the distance from sensor to FF
canon -> T-ring -> spacer solution -> AT2FF -> focuser.
44mm - -> 10mm -> 3mm
Then again i'm not a frac guy, perhaps someone could chime in to confirm how critical spacing is?