Thomas & Betts and AMP are a couple of manufacturers that make high quality terminals. Check with your local electrical distributors for the better quality terminals. Marine supply vendors generally have good quality wire (high strand count for flexibility, oil & gas resistant insulation, tinned conductors for corrosion resistance). If you choose to crimp your connectors, subject them to a "tug test" prior to making the connections. The crimp should withstand a good strong "tug" on the wire. Even a good quality properly calibrated crimper won't produce a good crimp with inferior or incorrect crimp terminals. (First hand experience on this).
If you have concerns about high temperatures, you can get Teflon insulated wire that will withstand the heat. And ifyou aren't sure of the proper gauge, go bigger.
Of course, none of this info applies if you want to retain the original style, and color of the wire.
Wayne