Here's a good (and detailed) list of everything required to swap.
http://www.mustangii.org/tech/tipsntricks/302swap.shtml
The list is a little scary because its geared to producing a factory appearance. Not everything is required if you are willing and able to do some fabrication, junkyard shopping (for a different radiator, etc.), or don't care for factory originallity.
As with any engine swap to another factory optional engine, having a donor car available makes it a lot easier. Junk V8 MII's can still be had pretty cheaply if you look for a while.
In a nutshell, here's what you'll need:
-If you have the small 6 3/4" rear (with the inspection plate), it will need to be changed or your 302 will eat it shortly. I have a '76 2.3L powered MII hatch with a factory 8" rear, so not all 2.3L's had the 6 3/4" rear. If you want to change to 5-lugs, use an early Granada or Maverick 8" rear. The spring perch width is only about 1/2" too wide and the axle width is right.
-The MII 302 used a smaller flywheel and bellhousing than most Fords, but the "standard" 157 tooth 10 1/2" setup will work...its just a little tighter in the trans tunnel. That early Granada or Maverick 302 will fit fine.
-The trans behind your 2.3L could be a C3...not a good choice behind a 302 even if it could be made to fit. A C4 should be easy to come by and pretty cheap. Again that early Granada or Mav is a good source if an MII donor is not available.
-Engine mounts are the real challange. The aftermarket Anchor brand replacement is incorrect. Ford has apparently stopped production, but your dealer may have a set on his shelf. Expect to pay $90+ for each side. The engine stands are available used. Check the MII used parts suppliers, and keep an eye out on eBay.
-The radiator can be had from an aftermarket source, or you can fit an aftermarket aluminum racing radiator with a little work.
-Fox Mustang 5.0L parts (engine/trans/rear) can be used with a little more work. There are technical articles on the web for swapping almost any of these parts into either a MII or another early Ford. The '83-'85 carburated 5.0L's are easiest (i.e. no computer or fuel injection), but there are a bunch of nice EFI 5.0L MII's running around. The T-5 is not a bad install, but the AOD requires some trans tunnel massaging. Even the 8.8" rear can be used if you cut the original suspension mounts off and replace them with spring perches. A plus is that it allows the use of higher offset Fox Mustang wheels and better brakes.
If you've never done this type of swap before, the list probably looks pretty bad. But as 4 cylinder to V8 swaps go, the MII is pretty easy due to the avilability of factory parts from the MII, Granada, Maverick, and Fox Mustangs.
I'd get your MII in good shape on the outside first (take care of rust problems, protect what you have from getting worse due to weather, etc.) then gather parts over time to do the swap.
Let us know how your project is going...