Aftermarket stereo install

[fatmxmnr]

new to the board...I am acquiring my father-in laws- 69 c/10 lwb...it has if i am remembering correctly an aftermatket am radio that he installed...looks stock. I want to keep the am radio in the dash and install a CD player with motorized faceplated angled out from under the bench seat...hope my crude drawing gets my point across. I plan to custom make the box the stereo would sit in. My question is do I need to do anything so that the heat generated by the stereo can vent out of the box? Also what kind of adjustments...if any will I have to make at the fuse box? THis will be my first stereo install in a vehicle of this age, so any tips or instructions would be appreciated...will post pics of the truck when it arrives in early June