If the metal in the doors is so rusted that the holes are enlarging as you work on them......you are going to have to replace the metal.....cut and weld... then redrill the holes. There is very little reason to putty up metal, hoping that you can get by. You will for a very short time before the whole thing falls apart. If your frame supports are rotted away, then they too will need to be rebuilt. Doesn't matter what type of pump as all these concerns are basic and should be addressed on each restoration. There is a learning curve on rebuilding pumps and you are currently in the beginners class. Good luck, Paul
www.severngaspumps.com 
