You guys are doing great things, please keep it up!
I'm also 5'10 so it should be good, I'm currenly on a large bike (60cm ctc) and I can ride it but it's too much of a stretch for me (my hands end up going to sleep cos I'm leaning forward too much) and I've got the seat dropped right in to the top tube (so there's very little 'give' if I step down off the saddle!), so I want something more like a medium. Looks like these were made in 51,53,55,59 and 61 so if it's a 53 or 55 I reckon is should be ok for me.