So, I've been avoiding level shifting issues in my own tinkering. This actually got me looking at various buffer/level shifter chips, purely in the interest of not 'wasting' two unused channels.

After reading the datasheets, it looks to me like, technically, the 74HC series reliably sees 3.5v (0.7 * Vcc) as high. I'm wondering, is the 74HC series really ok to use in this application? Would the 74HCT series be considered necessary, or just more reliable for a 3.3 -> 5v application?

In regards to chip options, any thoughts on using the 744050, 74244, 74365 or 4504 (4000 series) chips? The 4504 seems really nice, as it will do both up and down level conversion. The 4050 seems nice, in that it doesn't use OE pins and you don't need to tie unused channels high or low, though I haven't seen an HCT version of that. The 365 looks similar to the 541, just with 6 channels, and the 244 is similar as well, but uses the OE pins differently.