Steve R,
The sleeves I used are thin (3/32", .09375") wall thickness. I put in the thickness in decimal form so you can see it is basically 100 thousanths thick. This means you have to bore the engine out almost 100 thousanths just to get the sleeve to go in. Actually, let me get my brain in gear - it is early - the 4.25" sleeve is already .017" over std. bore, so you actually have to bore the motor .09375 + .017 = .11075"..... 110 thousanths! And I have insatalled MANY of these sleeves and never bored all the way through the cylinder wall and never had any problems. Maybe I have just been blessed with good blocks.
As for your question about sleeving a 427 block down, some racers used to take SO blocks and sleeve them down to 428 bore for racing. If you use a 3/32" sleeve you don't have much of a step at the bottom of the bore, but then again you don't need much. I guess this would be a good way to be sure your block would stick around for your grandchildren (assuming no rod caps go through the side).
Shaps,
It is pretty common for an FE motor to leak around the rear main seal, but not if it is done correctly. Lots of builders do not excersize the patience to get the rear main in correctly so that it does not leak. There is a trick to it. You can spend about 10 minutes looking it over real carefully and tell if it is leaking at the main or if it is comming from up top somewhere. Another spot notoriuos for leaking is the rear seal of the intake manifold. If the motor runs strong, sounds good (no knocks or rattles), has
oil pressure and does not loose water I wouldn't be afraid of it. You should ask him to cut open the
oil filter for you - go ahead and buy a new filter and quart of
oil for him. Look at the spark plugs too.