need advise in a 318

Any 318 made from 71 through 86 is basically the same. Heads all flow similar, same cam, same 2 barrel intake manifold (except for a few 4 barrels used in the mid 80's and on cop cars). Before 71 they were higher compression, about 8.5 to 1. After that they are pretty low compression, about 7.8 to 1. Note, the books say their higher comp than that but if you pull one apart and measure it you'll find it's almost always lower than rated. 87 up used a roller cam, or at least I think that's the year they started using roller cams. Some time in the 80's they started using the head casting 302. They are a better flowing head than previous yrs. and are closed chambers so the compression might be a little higher. Not much experience with those yrs. so I'm not positive exactly what years they were used. If your just looking for a block to build on their all the same up to the roller lifter models. Just look for the block with the least amount of wear. Oh yeah, 92 up are magnums. Roller lifters, closed chamber magnum heads, a little higher compression. But they have a different intake bolt pattern so you need to use a magnum specific intake. They also oil the rocker arms differently than the older LA engines.

Here is the only website I know of that has a bunch of info on small blocks.

http://www.moparts.org/Tech/Archive/smallblock.html

Hope this helps.