The seating of all the valves is not the only thing that must be checked,
when choosing to rebuild a head.  You haven't said that you've removed the
springs to check the valve-stem-to-guide clearances/ wear and cleaning of
carbon deposits.

> I used alcohol for the leak test. I poured it to the opposite side of the
> valves and check for sign of leak on the valve stems. Mine had no leak for
> 3 minutes and possibly longer than that.

  Removing the rods to replace the rod bearings and take the opportunity to
inspect and measure the crank's rod journals.  This may uncover damage
that'll point to a total overhaul; 'not checking' at this point in the
disassembly is a mistake.  One that may bite you in the ass sooner than
later.  It's not a huge step to go all the way at this point.

> Rebuilding a short block is something I have not tried.
>
> David