Wiring harness

Hey all. I'm thinking about getting a new wiring harness for my 74 225 plymouth duster. Any tips on where to get quality yet affordable options? Thanks
You need to do some basic homework first.
Specifically if the car was optioned for higher amperage equipment.
Start with looking where I suggested and we can help you understand what's there.

With that knowledge you can determine much more specifically what will be needed.
M&H may have a harness or they may be willing to make one for you.
If its a standard option, then and if its just engine bay, Bill & Rose Evans might have something. A little cheaper and some say a little less quality.
A used one from a car being parted, is probably the cheapest and depending on the life its led, could be pretty good.

The problems with any cheap kit is
(a) You will need to figure out how to adapt it to all the circuits and systems. They are rarely put together by people who know Chrysler electrical systems.
(b) You will need to figure out how to route it and connect it. The factotry did a decent job. Try to follow their routing nad support if the kit allows.
(b) The materials supplied will be cheap, skimpy, and inferior. Copper is expensive. Wire with insulation that is tolerant of oil, gasoline and heat is more expensive than general purpose automotive wire.

The problems with a more expensive kit is you will still have to do some figuring out of the wires and where they go.
IMHO for what you are doing, and your current knowledge, it would be easier and better to rebuild your harness and/or work with another used one. Why? Because most of the wires you'll be able to follow where they go and what they connect to. You'll know this because you will have tagged or labled each connector before taking it off and because you'll take lots of photos.
Cost will be less, and time will be less than a kit, but more than a pre-made harness.