First time, long time.
Mine was a ‘68 Buick Electra 225 Limited, coupe (2dr hardtop). 430 w/ 4bbl. Power everything (including trunk). Inherited it for $1 from my father. He stepped up to the ‘73 deuce-and-a-quarter, 455! I had mine airborne once. I would attach a picture but I don’t know how.
I'll bet your '68 still had the 10.1:1 compression ratio, too, like my 1970 Electra did. After 1970 the compression ratio got whittled down to 8.5:1 a whole 15% less power per cylinder travel stroke in spite of the 455 cu in. (or in Cadillacs the 472 or 500 cu. in.)
My company cars are all 1970 Cadillacs of one sort or another now. They are all 10.1's