Heater box question...

[n737nc]

I am trying to get some kind of idea on what to do with my heater.
I really like the looks of a shaved firewall, but sometimes you need to have heat(don't want to put my truck up for 5 months because of no heat).

I see some people have shaved firewalls, with two heater lines run into the firewall and no heater box in the engine compartment. How is this done? This is the direction that I would perfer to go. Keeps the engine compartment clean, and have heat.

Also, if I decide to use my stock style heater box, what is the best way to clean and paint it to look better? Is there a way to get it smooth, and painted with a gloss finish to match the firewall?

Thanks,
Nick