I have a 350 that I was going to put in my 1980 K20.
Upon dissassembling the engine it seems to be bored .080 over.
The bore dia. is 4.078
I was going to have this block cyl. trued but is this going to be possible now? or is this block junk .
Thanks for any help.  

I have never heard of this on a 350 as block cyl wall core is pretty thin to start with. I have seen .060 over but unless sonic tested before is unwise to attempt. Look for another block as yours has seen the end.  

I have seen this...my son worked at autozone for a short time. I saw two 350's go out the door at .080 over!! .080 is over the limit on most blocks and can be done with very few. I would never consider a .080 bore on a standard GM 350 block. look around you will find a good std or min. overbored block at a resonable price.  

You surely can't have it bored anymore - it's probably near finished now. I wouldn't trust it with any nitrous or any kind of significant power gain over stock.  

You might be able to get away with a hone job, that's about it. You need to have the machine shop check the cylinder walls for cracks and stability though.

Some small blocks you can go .090" over with, but it's very dicey because the cylindre walls get so thing and you have distortion issues. But some production blocks can take it (usually the earlier ones) because they had a higher nickel content and were stronger. Some late model truck blocks are still like this too, so it all depends on when your block was made, and what it came out of.

I worked at Autozone myself while in school, saw some crazy things with those rebuilt engines too!