red67 said:
What is the most desirable year to obtain for a swap? Are blocks or heads better some years than others? For a performance build up, what block year should one look for?
%) just curious...
This is a bit of a loaded question. The choices depend a lot on what you plan to do. If you just want to pull something out of a junk car and drop it is will be a different recomendition if you want to pick up an engine and do a cheap rebuild, wich is different then if you want to build a high dollar engine.
If you can get an engine in perfect condition that isn't worn out and in need of a rebuild and you don't want to do anything to it, the '69-'70 is the best. the 4V having flat tops and more compression the better choice. Now the chances of finding a 35 year old engine that is perfect are not good.
If you are going to build something, the post '71 blocks have a little more deck height and that is what most of the aftermarket considers a standard 351.
All stock heads suck. The 69-70 heads suck the least. If you don't get 351 heads, the bolt holes on the 289-302 heads can be drilled out. For good heads, look aftermarket if you can afford them.
Late model 351s are roller cammed. This is a great performance/anti-friction upgrade. Also late model blocks are newer and haven't had as much time to wear out. Modern machining has better tolerences then the stuff of old. Also late model blocks have 1 piece seals, much better at controlling oil leaks.
As far as I know, there are no "bad" years for 351s. Some years were heavily smogged, but if you rebuild a '69 and a '79 to the same specs, they will run the same. Don't worry about the factory HP ratings unless you plan to drop in the engine bone stock, including the convertor and air filter.