You'll want to source a Mustang II specific oil pan if you're able, but a front sump isn't necessarily out of the question. Here is some more info in that regard, including the specific part number.
Here's a quick how-to on changing an oil pan gasket on a 302 without removing the engine. It's the same steps as changing a starter more or less, so it's basically 2 birds with 1 stone.
First, raise the car to an appropriate height and support it. Remove the (-) battery cable from the battery.
Pull the mounting bolts from the rack and pinion. You're not going to remove it, just manipulate it so it's out of your way. In my case, I lifted the right front tire from the pedestal it was on so that side would turn freely.
Remove the cable from the starter.
If your car still has the secondary cross member bolted in place, remove it. That gives you access to the bottom starter bolt as well as clearer access to the back oil pan bolts. Remove the starter by removing the 2 bolts holding it in.
Remove the sway bar bushings and brackets from the frame and let the sway bar hang.
Remove the oil pan bolts and remove the oil pan from the car. I had to wiggle it over the sway bar and out of the car.
This picture is to illustrate the difference between a II oil pan and another stock front sump pan. I also have a picture of the part number for the oil pan. I'm not sure if it's the complete part number or not, but what I have is still visible. The II pan is behind the standard.
Installation is the reverse of these steps. I purchased the newer one piece oil pan gasket which comes with threaded plastic retaining clips, they're extremely helpful for reinstalling everything.
You'll also need a set of II specific frame mounts and motor mounts. The frame mounts are generally where the problem comes in if you don't have them in hand. They're a little on the scarce side anymore, but the motor mounts themselves are available through classicautoreproductions.com :
Finally a kit that fits a Ford 302 engine into the Mustang II engine bay. This kit is modeled after the factory kit with the OEM mounting points, but bolsters durability in key areas. This it comes ready to bolt into the car for either a V8 swap project, or just to replace your old worn out...
classicautoreproductions.com
There are a few other 74 specific issues that need to be worked around, but I'll let those who've swapped a V8 into a 74 speak for those. @extra_stout