1985 chevrolet Hello im in need of a new engine and i will be swaping my 305 for a 350 now im looking into buying a 350 and rebuilding it then just swap it out. now my funds are tight how much would a 350 block in need of a rebuild cost? And then what should i look for? i heard not all blocks can be brought back to life is that true?

1 - Anywhere from free on up. At least that's what you can get them for in PA. Personally, I wouldn't pay more than $250 for a good rebuildable block.

2 - That all depends on what you want to do with it and how much money you have to put into it. If its not cracked it can usually be rebuilt. The only thing that will really determine if the block can be rebuilt is the block. Heads/crank/pistons/cam/bearings/etc, everthing else can be replaced. In some cases, like bearings, they MUST be replaced. Pull the heads and check the cylinder walls. You won't be able to see the entire bore on every cylinder because of the pistons, but look at what you can. Check for scratches/deep grooves and cracks. Turn it over and pull the pan. Check around the main caps and their supports for cracks and chips. Take a caliper to measure the cylinder bores to make sure they are not at their limit. Ideally they should be right at 4.000" and not more than 4.030" so you can have them bored if necessary.

If you want to do this as cheaply as possible, check the crank journals for scratches/scoring/pits and the pistons for the same. Check the heads for cracks/bent valves/broken springs. Check the cam & other bearings for wear. Normal wear/small scratches are fine but if they are real bad it can be a sign the engine was starved for oil(like in my truck).

3 - Yes, its true. Although the vast majority are good for rebuilding, some take more time & $$ to bring back to life than others do. As long as the block is not cracked and the cylinders are at their size limit(usually .060" oversize) then you should be able to rebuild it.

For the '87-up blocks, which are the best choice because of the roller lifters and the 1-piece rear main seal, beware of cracks in the lifter valley. These blocks can be had for $100 around here.

The 1-piece rear main was on all of the 87+ blocks, but some trucks were a bit late to the party when it came to hydraulic roller. something to be on the lookout for.

best cheap stock-ish setup I can think of -
1pc rear main
4bolt
vortec heads

Good point about the truck engines. However, since the OP is in CA I'm pretty sure he has to stick with a car engine anyhow to pass smog.

Also, to get 400HP a 2 bolt should be just fine.

Oops, missed the CA part. That definitely makes things more difficult.