then you should be good to go on the parts swapping. The electronics shouldnt be all that difficult either. the computer for the e4od will not work for the aod so you will need the computer for the aod for it to work. what part do you have a problem with? Bad tranny or bad engine? The 351 and 302 use the same bolt pattern so you could swap motors or trans unless you just want to swap both. I myself am partial to the 351 over the 302 but thats just me.
EDIT; i just reread your first post, some how i thought that you were wanting to swap the 302 with AOD in place of the 351 with E4OD. Replacing the E4OD with the AOD has been done and documented here but i dont know what has to be done to make it work. It will bolt in just fine. But the E4OD uses more electronics and the computer will be looking for inputs that the AOD will not be giving. So i think a different computer from a truck with a 351 and AOD would be required. As for the steering column differences in dash shape and the wireing for the wipers turn signals and such would need to be delt with for the steering column to work.