I have the two zone boiler system, the upstairs hasn't worked for 4 years due to air in system, not really worried though gets real warm anyway. The down stairs pump seals started leaking, not used all summer.

The question is is it possible and how hard would it be to change the pumps around, and what is involved, and are there still parts available for the older boilers?

The other queation is since the only thing the boiler is used for in summer is to heat the water, can I put switch valves in so I can just use the hot water tank as a hot water tank not a storage tank?

The question is is it possible and how hard would it be to change the pumps around, and what is involved, and are there still parts available for the older boilers?

Just buy a new pump and install it or repair the old pump with a new bearing assembly etc. Changing the pumps around is false economy.

Almost all parts should be available for your boiler.

Yes you can just install a electric heater or gas for that matter and rearrange the controls on the boiler. No problem.