340 block,what's it worth?

.040 for pistons you have? Or did you just have it bored? When an engine is bored and honed it is fitted for pistons you have. Being you said they used torque plates they are used when power honed. So it must have been honed for pistons in hand. That info will be important on determining its value. Every piston manufacture is a different final size.

The next bore on a .040 will be .060.

Std. bore blocks $500-$1000 . .030 would be less and so on if you do not have the pistons. a .060 block would almost be useless unless sleeved. Unless its a fresh bore with the pistons. Torque plates are used for honing to size . Not boring.