How to remove ul li formatting from list of attributes in Ubercart order email template?
Not exactly what I was asking for, but I did find a workaround that works for the most part. I copied the uc-order--customer.tpl.php  file into my theme dir and added css for the ul to the head in that file. (display: inline-block and a few padding, margin, and list-style styles). The only issue now is the emailed order invoice. The CSS doesn't follow along into the email, so it's a bit of a mess. Open to any suggestions on how to handle that, or a better way overall.

EDITED TO ADD: I ended up copying the product line items from the uc-order--admin.tpl.php file. The attributes therein are not styled as a list, so it was a breeze to use that code.