There are about 12 different O2 tank sizes and capacities but I would want to check the other tanks they have in inventory to see how they compare. 600 #s to start does seem awfully low.

There are also different acetylene fittings as you have discovered. Sometimes the solution is as simple as buying an adapter but ALWAYS be cautious that any torch tip you may use will not flow more than 1/7 the capacity of the acetylene tank. Acetylene is highly unstable so it is stabilized with acetone in the tank. If the acetylene is withdrawn too quickly the acetone comes out with it and makes the tank dangerous. Also never run your torch over 15# on the acetylene.

Torch tip manufacturers provide flow info for their tips and torches. As a rule of thumb, get the biggest tanks that are practical for your application. The gas is also cheaper per cubic foot when purchased in larger quantities.

I was just browsing for relevant blog posts for my project research and I happened to discover yours. Thanks for the useful information!

Here is a link that might be useful: http://www.longevity-inc.com