been doing some homework and from the looks of it, with the 460 being 1" taller than a 390 and the Dearborn kit mounting the engine 1" higher your not going to be able to put much of an air cleaner on there...I ran into another post on the forums saying to modify your 390 mount and you will have a nice fit. I will give the guy a call this week and keep you posted. Doing this on a 68 myself.
from all the info I have been reading unless you want to cut a monster hole in the hood fab mount which one be that bad or mod your 390 mounts I will take pictures of my final mount when I'm done prob a couple weeks out, still working on paint at the moment.
Did U do this swap?I have a 460 in my 66,with the edelbrock it was close,the holley sits lower and I put a spectre air filter kit on it,works great,had the car since 76,also has a E4OD trans.Then I bought a fiberglass teardrop,so tons of room.