i just bought this engine and i took it apart to see what it was like and found these, this isnt the first 86 iroc tpi engine ive taken apart and found flat top pistons, i took the original one in the car apart a couple days ago and it had flat tops also, i can see marks from a hone in the bores and they seem to be in good shape, just need cleaned, but anyways, are these stock?

 

AFAIK yes they are.

 

Yes. 87 was they year they went to (slightly) dished pistons in 305 TPI engines. 85-86 were all flattops.

That's the reason compression ratio was 9.5:1 in 85-86 but 9.3:1 in 87-92 305 TPI engines.