DIY 5mm Infrared spot?

Short and simple: 200 IR 5mm leds with 1.4v(50Ma) drop each. Input voltage is either from a 6V or 12V source (motorcycle or auto battery), whichever is ideal. Online sourced calculators gave suggestions of [50 parallel strings of 4 leds and one 8.2 Ohm resistor for the 6V] and [25 parallel strings of 8 leds and one 16 Ohm resistor for 12V]. Two questions at this point. * First - which of the two (6V or 12V) seems ideal when considering portability and heat dissipation? *Second - considering the power source, is a v. regulator between the source and array unavoidable (especially when considering the longevity of the unit)? ---Kudos on an awesome collective of shared wisdom and ideas ~ a.k.a. candlepowerforums.com---