Im no expert. I know the 73 and up blocks were supposed to be better castings. The block is good replace the rest for a performance build. My block is a 73 block thays girdled and all.
The later blocks, 1975 and 1976, and are sometimes called "blue blocks". I believe they had beefier castings. The combustion chambers on the heads got larger and larger causing compression to go lower, so they are boat anchors at best for any type of performance. Earlier 455 heads or 430 heads will be much better. Or, what the heck, get a set of TA SE1's and have some fun. 66cc - 70 Stg 1, one year only, rare 69cc - 67-70, 400 69cc - 430 from 67-69, most 70 455 heads 71cc - 71-74 78cc - 75-76
Evaluation? As in money? If so i dont see much money going for any post 1973 Buick car. Some one this forum told me a 455 is a 455. Its how you build it.
While the shortblock is pretty much the same year to year, when building one if you want power, heads is where you spend your money. The carb/intake and exhaust will naturally follow. But heads is where the real power is. And a good set of ported aluminum heads will run you $3K and up.
