Runs, then dies suggests fuel (spark is usually all or nothing).
I'd suggest cleaning the carb carefully.
I hope you cleaned the oil pan and checked the pickup, lubed the cylinders and checked for oil pressure too.
I would hate for a minor problem to cause a major problem when running.
Also, if running it for a while, keep an eye on temps.
The water distribution tube is a common failure on old sitting engines.

http://p15-d24.com/forum/20-technical-archives/

Remember, those older engines run well when properly maintained, they just need more maintenance than even 1960s engines. Waking one after years takes a bit of effort!