I don't know how I've missed this thread for so long.  I have 3 used 40 horse pistons and cylinders out in my garage somewhere.  I had a 40 horse block that had been line bored.  I haven't gotten rid of it, but I haven't seen it in years.  In fact, the rest of the engine should be somewhere in one of the piles of junk in the garage.  It was a complete engine that would turn over and had compression.  I gave 50 bucks for it at Bug-A-Paluza (since we've had more, that's now known as Bug-A-Paluza 1), brought it home, tore it down, had the block lined bored . . . and moved on to other projects.  That was 1999.  I know where 3 of the pistons and cylinders are.  If you need anything else for your 40 horse project, I've probably got it . . . and I probably can't find it . . . but you are welcome to it if I can.