Just found a pair of ST-r500 flight deck shifters on Craigslist for super cheap (maybe a divorce or a rich person's old take-offs??). Anyway, their loss is my gain, right?

I bought most of a 7400 group back in February (2x8), and I was thinking of replacing the downtube shifters with these. Can anyone think of a reason why they wouldn't work? I saw a review on Amazon that said a guy had trouble getting the shifters to reach the last 2 gears on his 7403 group. I think I am going to buy these either way, but are there any thoughts on the subject?