Have you checked with local machine shops to see if one would donate their time to show the boys how to machine a block and head for rebuild? If the block only needs cleaning and honing, they may do the work on the head for you just for cost on any parts.
When done you might get with a local car club and see if they would let you auction it off for a fundraiser at one of their events.
When I was in school we fixed up a donated Pontiac station wagon for our VICA club. Most all of the parts were donated, or bought by us at cost. We sold the finished project to pay for several members to go to the VICA nationals.
