Worth the trouble?

The motorhome 440 suffers from the same problems you already have which is no compression .060 down in the hole pistons so If you decide to build the 440 you will have the same concerns as now. Did you ever think about picking up an old 360 somewhere(about $50) and getting some pistons for it$225-$400) and having someone balance the shortblock(probably $200 counting mallory metal) and then just do a weekend swap and stick it back together.