[TorqueInc]

Kinda lost me there but..

There is alot you can do to improve the 425 besides just"rebuilding it"
One thing you can do is make the engine larger
A .040 overbore would be a start
Some head work including new valves,port work(nothing exotic),springs and a .020 cut off the face would do wonders.
a camshaft designed for the engine (torque cam 218-224@.050
Good sound machine work and a 472/500 intake manifold(modified)rebuilt Q-jet.
Headers if you have the skill to convert a set or buy some sandersons
You would have a good strong runner that would get decent mileage
I know of several good running 425's that have alot less that what i described done to them and are driven daily.
Nothing to it
a 472 or 500 would be better for power but you would be pissed at the pump as well.