[454HO]

I went thru this same exact decision process a few years ago. Obviously from my screenname, I picked the 454HO crate. Why? My truck was a BBC from the factory, so the mounts were already there. It also had the Chevy bolt pattern TH400 which just needed a minor 'freshening'. Switching to the Caddy motor would have required either an adapter or a BOP pattern trans.

Some other things I didn't like about the Caddy motors are the valvetrain, lack of off the shelf headers, and the oil filter placement. The stock valvetrain is supposedly a major limitation on the upper rpm limit of these motors. But I think there are kits to beef up the rocker arms to take the stress of higher rpm levels. And for headers, supposedly you can use BBC headers after you cut off the head flange and weld it to a Caddy flange. The oil filter placement is just a personal preferance thing mainly, but it could result in interferance issues in some chassis.

It is definately an interesting motor. I personally just went the easy route and stuck with Chevy.