Kristen,
Let me be perfectly honest - I've only had limited experience with Balcar lights for stills, and Kinoflo for cinematography.
What I would suss out from what little you have mentioned, you would be looking at several heads, and all the accompanying basic accessories. I am not familiar with the Lowel set, but what I would look for in a professional set would be the entire available range (for future expansion needs), performance and reliability, after-sales service and replacement parts (and cost within a certain region) as well as what I simply refer to as 'rentability'.
What I don't have, or don't want permanently, or can't buy at a certain location or in time, I would look at renting as a viable option. At least, if I were shooting professionally, as you hint towards, the rentability factor is something I would seriously look into.
Have you considered renting...at least just for this project? Also, would you consider a different approach? I have seen beautiful still portraits taken on the fly with cinematic lights (aka: Kinoflo). Colour balance needs to be addressed though as the Kino tubes are inherently warm (think 'hotlights' without the uncomfortable working temperatures).
Like I mentioned at the beginning, I hope that a few much more experienced photographers would chime in. I am only a rank amature who dabbles (and quite woefully might I add) in the dark art of photography from time to time.