Chevy 283 holes in pistons

I tore down a 283 on Saturday that I picked up to rebuild to put in my 63 chevy truck.This engine was complete from pan to aircleaner . the guy I got it from had it in a 66 that he bought and he said it would not run and one cylinder only had 30 psi on it so he pulled it stuck it in the back of his garage and bought a big block for his truck.What I found in the engine was a hole in 2 of the pistons and all the pistons had been intalled backwards in the block with the notches facing the back of the engine.Its looks to me like some one at some point tried to put new ring on the orginal pistons .None of the rods had been stamped in order from front to back and the block is standerd bore.There seems to be no damage to the cylinder walls that I can see and the crank and piston rods look fine.This block has casting numbers of 3756519 and date of J250.I plan on taking it down to the machine shop and have them clean it and magnaflux it.Do you think this has caused ant major damage to the block?
Thanks for any help you can throw my way.
Jim

no hanging the pistons with notches to back of block will change the pin off set some. this would not help or hurt much . the 283 did not have or needed much wrist pin off set. i would think not that much has the crank stroke is small . in a rev rotation this was common to put the notches in to back of block for marine use

Here's a good stout hypereutectic piston. Note that the compression height is 1.805" This is the type of tall CR piston you will want to use. It will allow you to get to a 0.035" to 0.045" squish (zero deck) without taking too much meat off the block decks.
KB Pistons for Automotive Applications

I was just writing this for a member on another forum, but it will suit you as well......

First thing you will want to do is determine the stack you will use. On a 283 Chevy, the stack of parts used is the sum of the connecting rod length (5.703"), the radius of the crank stroke (1.500") and the piston compression height (measured from the centerline of the wrist pin to the crown of the piston. This measurement for a 283 is normally 1.800", but there are "rebuilder special" pistons that have a shorter piston compression height. They are made shorter so that if the machine shop decks the block, say 0.020" (twenty thousandths) to freshen the surface, then you can buy pistons with a 0.020" shorter compression height (1.780") and maintain the same piston deck height. Best advice is to purchase 1.800" (or taller by a few thousandths) pistons. Choose a piston crown configuration that will work with the cylinder head combustion chamber volume to produce a static compression ratio that will work with pump gas without detonation. Current thinking puts this at 9.5:1 max using iron heads and 10.5:1 max using aluminum heads.

Take the block to the machine shop and have the technician check the main bearing bore for being round and parallel. If the holes are out of round or do not line up, have the block align-honed or align-bored to correct the main bearing bore. This is the cornerstone of the motor. If the mains are not machined to factory specs, then everything else will be skewed in the motor.

Next, knowing the stack of parts you will be running, have the shop to index the block off the main saddle and cut the block decks to zero piston deck height. For instance, if your stack measures 9.008", (1.805", 5.703" and 1.500"), then cut the block decks to 9.008" block deck height from the main bearing centerline. Most small block Chevy blocks will be in the 9.025" block deck height range from the factory. What we're doing is setting the block up square so that we will have the proper squish using a 0.039"/0.040"/0.041" head gasket thickness. We're also squaring the block so that the heads will sit squarely and properly on the decks......so that the intake manifold will sit squarely and properly on the heads and will seal up each and every port so that you don't have any vacuum leaks or any cylinders pulling oily vapors through the bottom of a port that is not sealed up because the heads are askew on the block.

Resist the urge to use anything in the oiling system other than stock-type parts. If you want to use a larger capacity pan, fine, just match the oil pump pickup to the pan, leaving about 3/8" clearance between the pickup and the bottom of the pan.