1978 Camaro Z-28 Motor Swap
 

Kinda Undecided .

Big block Chevy (Bored 427CI Truck block or 454CI )

Or Small Block Chevy (400CI or Rebuild & maybe Stroke the original 350ci)

Go with the 400 ci small block 30 over with a 6 inch rod

What kind of power will that get me??

Depends on how much you want to spend.
I built one for my old camaro using the 6 inch eagle rods, dart sportsman 72 cc heads, weiand stealth intake, 10.1 pistons, stock crank, holly 850 dp and made 472 hp 518 ft/lbs of torque on pump gas.
All the parts and machine work came out to around $5000

The Heads are the most expensive part I am guessing.

I could build a Big block that puts out around 700hp/620tq For the same money.

Plus it's an all forged rotating Assembly so I can Spray the hell out of it.

Youve been reading too much car craft and super chevy mags.

If you have the block and crank already and really good set of heads to work with, you mite make that kind of power for $5000 on top of that.
HP aint cheap.
The carb you would need alone would cost you about $800

go for the 427 bbc but make it a stroker

whats your goals for the car? straight line or cornering or all around package?

Well i would say you have 2 options big block or small block
big block cast iron straight line performance because of the front end weight it alters your handling.
Small block is an awesome way to go but lack some torque limited performance potential in comparison to big block.
The happy median is AN ALUMINUM BIG BLOCK AND ALUMINUM HEADS
Keeps the total weight down to approximately stock weight and limitless potential