They're not cheap but it's the only game in town... I think I paid about $800+ for it. It does fit nicely but it requires you to go from the standard truck mounts to a side mount system and rear/trans-tailshaft mount.
I'm still building mine. I have some pictures which I'll post in a couple of days.
I chose an E4OD since they're used up to and including the F450 and behind the 300(6), 302, 5.4 V-8, V-10, 460, 7.3L Diesel, etc.....
Mine came out of an F-450 diesel. I had a transmission guy build me a trans using the trans-case from a SBF/300-6 using all the heavier duty parts for a diesel including the rear-mounted parking brake that came in the F-450 and motor home chassis' (The F-600 doesn't have parking brake provisions in the rear brakes)
I'll also add that I am sticking with the 292 because it'll look "right" under the hood and more importantly, It'll SOUND "RIGHT" too.
If I didn't use the Y-block, I would probably use an EFI 300-6