Wow, seems like such a waste, those pistons will work however not well like a new set.
If you have been told this by a mechanic why not ask him? Why come here after the fact and propose this question?
You may feel the grooves but in comparison to new pistons they are well worn, not only that now the skirt won't hold the oil as well as it can with the grooves. That wear is from the piston rocking in the bore some and lack of oil. Now you are going to put worn out pistons into practically a new block?
Why did you not try to find a good running engine instead of doing this level of machine work, sleeving the block and then using old worn pistons?
May as well wear a ****** and then rinse and use it again to save money too!
As I said in PM before we here know what it's like to be young, however we are also aged and have enough experience doing this stuff to really offer solid advice.
Seriously get new pistons, if they /hone/bore those sleeves to match the used pistons I'll be amazed, as the sleeves need honing to match the pistons that are going in.
Good luck with this however you choose to do it.