Does it cool adequately? If so, then why change it? Since it is a '68 428 in a '67, I'm assuming you aren't overly concerned about numbers matching? If you want to replicate as closely as possible, I would say switch to an 8 bolt.
1968 400 Coupe, verdoro green, black vinyl top, auto 1969 GTO Judge coupe, Carousel Red, manual 1971 Trans Am, cameo white, auto 1970 Buick Skylark Custom Convertible 350-4(driver), Fire Red, white top, auto 1972 Buick GS Stage 1, Royal Blue, black vinyl top, auto
