Big block isn't the issue as Chevy put a big block engine in the 1967 as an option. In your case it will be the need for a set of motor mounts that will fit. Once again this is a non issue if you have access to the car the 500 cube Caddy engine came out of. A Cadillac Brougham is just a Chevy Bel Air with an additional ten inches of leg room added to the rear foot well. Everything except the roof, and floor pan, and the frame off the Caddy will interchange (bolt on) with your Chevy. So grab the frame stands off the Caddy and bolt them to your Chevy, I would unbolt the A-arms and grab the springs as well. (note the Caddy also has four added diagonal braces at the corners of the engine compartment that stiffen up the dog house (front clip) of your car if you want to bolt those on as well).
The Caddy used a BOP bolt pattern TH400 as the Chevy part has a different bolt pattern at the engine, but will other wise bolt right in. The rear end should be a twelve bolt so I would snag that as well as the drive shaft (the TH400 has a bigger out-put shaft than the TH350 used). The heavier Caddy had bigger ball joints (stronger) to counter the added weight of the big caddy motor. If you can grab the A-arms they will bolt up and they will be stronger than the Chevy part. Caddy had bigger brakes (and bolt patern on the wheels so that could be a problem). The anti-roll bar up front is bigger so it would be nice to add to your list. Chevy didn't have a rear roll bar except on SS models, so the one off the Caddy would be nice to have as well; but it bolts to the control arms so you need those too. Final difference would be the gas tank. The Caddy had a 6 to 8 gallon bigger gas tank than the Chevy did (because the motor drank more fuel).
Inside the car the Caddy had luxurious appointments as standard equipment. So a AM/FM stereo radio with a tape deck was standard equipment, dual comfort zone controlled A/C, real leather powered seats, real wood veneer( instead of plastic) and a map light added to the dome light as standard equipment as well as foot well lights, glove box light, and lighted console as well if it has a console (not many did but it looks good). If you grab the light you will need to strip out the wiring harness from the Caddy to power it.
Any way you figure it a Caddy makes a great donor vehicle to upgrade the options on your Chevy.