<VV> flushing out brake lines for DOT 5

[Wayne Broadhead]

Hello everyone,

My son just bought a '65 Corsa and he pulled all the wheels off and 
noticed that both rear wheel brake cylinders are leaking and both sides 
shoes are soaked.  Since we are rebuilding the brake cylinders and 
putting new shoes on, he wants to know if this is a good time to flush 
out the old DOT 3 brake fluid and put in DOT5.

Can we just open up the bleeder valves on each corner and bleed thru 
some solvent or mineral oil, or alchohol....then flush that out and put 
in the DOT 5?   Would that work?

What should we flush the system with?

Thanks alot,
Wayne Broadhead
Bonneville Corvairs
66 coupe
65 vert