Just in case no one's figured this out yet, you can boost your team of lowbies using your 80 with LFG.
I misunderstood the first opening sentence. By lowbies you were referring to anyone under 80 (in this case your mid-60's). For whatever reason, I initially read it as the lvl 80 could que up with any four-member team... but only up to a unknown level. Thank you for both clarifying and the topic in general, I haven't messed with the LFDungeon tool yet.