Over the summer i am going to buy a block out of a junkyard and rebuild it and modify. I know the 350 will basically bolt up to my car. Is the 400 the same way? Or will i need a whole new set-up? Overall i am wanting to spend 1500-1800, doing most of the work myself, other than the machine work. What do you guys think?

 

350 will certainly cost you less. 400's aren't worth bolting in without some modifications, such as cam and heads. They also require externally balanced damper and flexplate, which a junkyard engine should have on it. But, most externally balanced flexplates are 168 tooth, making starter choice interesting.

You could do a decent 350 for $1800, but probably not a 400.

 

That is true the problem is that of the balancing on a 400. However they make an extrenal balancing plate, to go between your flywheel and the crank to balance the engine and allow you to use the original flywheel and tranny. The plate costs about $15-20. Trust me do the cam and head mods on the 400 and your friends with the 350's won't know what hit them.
Later, Garrett

 

The '87 engine will have a one-piece rear main seal, and the 400 two-piece. So, a different 153T flexplate will be required, even with that balance plate. There's no way around the harmonic balancer.

Of course, if you spend the bucks to have the crank internally balanced...

 

Let me get the ball trolling here on this 400 setup. A 400 will cost about the same as rebuilding a 350, plus have a more Cubic Inches. As for the rotating assembly if you want the to use a 350 flexplate and harmonic balancer you will have to get a 400 Internally Balance Crank. The cost between the 2 is about $20.00 more. If it was me this is what I would do but a complete Internally Ballance Assembly and use the 350 flexplate and balancer.
I guarantee you can build a Very Nice 400 with some decent heads and cam for $1800, the parts are not that more expensive than the 350. Ok, you will have to drill steam holes and the heads which you can do or let a machine shop do will be the only difference in price. one other thing, have the machine shop tap a hole for the starter then you can use you orginal starter.
In closing, I would say that a 400 would cost a maximum of $75.00 for parts and machine work. Also you might want to use the largest rod possible like the 6.0 rods, 400 came with small connecting rods.
Thats my Opinion
Remember there is NO Replacement for Displacement.