As a previous owner of Cadillac 3rd generation De Ville (a '67 Coupe to be precise) one small frustration of ownership was the lack of aftermarket parts support for Cadillac 429 (and later 427) cubic inch V8. You can certainly find stock rebuild parts, but forget building your big block Cadillac into some kind of street terror without spending serious cash on things like custom ground camshafts. The easiest way to go fast is to do what this next seller did and add a V8 that has a huge aftermarket support and start roasting tires like chestnuts at Christmas time. Find this 1970 Cadillac Sedan de Ville offered for $8,000 in Orange County, CA via craigslist.
A quick thought about matte finish paints...like boy-short hair on a woman, it has never, in the history of the known world, been an improvment. From Sinead O'Connor to Kaley "the Biebs" Cuoco, short hair on a lady is a downgrade, and despite what the tatoo'd stylist/customizer might tell you, matte paint on a car is also a downgrade. The end product might look fine, but standard shiny paint is better. Always.
Under the hood is a 455 cubic inch Pontiac V8 that has been massaged with ported/polished heads, big carburetor, dual exhaust, and high lift cam that is mated to a built TH400 transmission. The engine/trans in the deVille is canted back at such an angle that the driveshaft is multi-piece with a coupling (called a double cardan constant velocity u-joint) that allows the interior cabin floor to be almost totally free from the typical tranny hump found in most 60s/70s 'Merican cars.
See a better value per pound on a big classic? firstname.lastname@example.org