360

Before you get too giddy, you need to make sure that block hasn't already been bored too much.

If you have the pistons, you can look for numbers stamped on top. For example 030 stamped in the top of a piston would indicate that the engine is bored .030" over stock bore. If you don't have the pistons, you can use a set of calipers to measure the diameter of the top of the bore and compare it to the stock bore size of 4.00". The reason you measure at the top is because the top doesn't wear much because the piston rings don't go all the way up.

Once you have established the bore size then you need to assess how much additional wear the engine has. With experience, you can guesstimate the wear by feeling for how much of a ridge you can feel at the top of the bore. Alternatively, you will need some special tools to actually measure the bore at various points.

If your bore is standard size or up to .030" over it will probably clean up with a re-bore or maybe even just a hone. If it's already bored more than .030" over and has a noticeable ridge then the block might not be worth rebuilding depending on how much wear it has.

Once you've done all this, the next step would be to have it hot tanked and then magnafluxed to check for cracks.