Currently I have a 200ci I6 in my 65 Mustang, I'm looking to swap it for a 302. Does anyone have any idea what all I will have to switch out in the process?

 

Motor mounts and v8 spindles are a definite switch

 

I will forget something I'm sure.

V8 suspension, front and rear including spindles and axle and all steering components.
Motor mounts, radiator, driveshaft, gas pedal, exhaust.
5 lug wheels, probably new tires.
Fuel line on a V8 runs outside the frame rail to clear the exhaust.
If you get everything from a donor car, count on replacing all brake components and most likely all bushings in the suspension and steering.

Lastly, make sure your car is in better shape than the donor.

You can cut corners but you shouldn't.