what motor do you recomend?

i'm gonna chime in with my personal experience...

66 cuda
started out with :
1968 318 4bbl 904, 3.23's
front discs
front and rear sway bars
ss springs
6 cyl bars
poly bushings
8 1/4 sure grip rear

good driver - 14.7 @90 was the best in the quarter

last year I upgraded to a

78 360 as previously mentioned, and the power upgrade speaks for itself... from 14.7 to 12.80 is not too bad for a stock long block - 78 heads with 1.88's and all -
it still hauls with 3.23's

they are light enough to make any motor fun in them but for over the top i'd recommend big block... it's gotta be the easiest way to have a mild motor and run 11 seconds, with a good converter and gear...