>The 12 VDC in measures at 61ma. add another 10 ma. for the LCD display.
>The ambient in the area can get to 120F or so.
>
>I'm assuming I need a heat sink, probably prefer a heat sink on the
>board, but could screw the grounded tab of the 7805 directly to the
>aluminum box.

You are in an area where using a switchmode converter is a serious 
consideration. You will find something in the national Semiconductor "Simple 
Switcher" range, or Linear Technology devices will fill that bill nicely. 
You should be able to get an SO-8 package that handles 100-150mA, and people 
like Coilcraft make inductors that drop in to the circuits these chips use.


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