Surveyor, surveyor, surveyor.....after you decide which boat pulls at you.
You certainly should not need a new mast...if you do run away!
Standing rigging, they are about the same age on both based on your statements. Really depends on use and care more than age. Many boats still have the same standing rigging 20 or more years later, but it gets costly when it has to be replaced.
20 plus year old sails will need to be replaced if you want performance. The 10 year old sails might be in the same condition as the 20 plus year old sails dependent on use. Some people replace sails every two years because they race and work them hard. Some wait 10 years, and some obviously never replace them based on the Tartan you are looking at. Sails will cost you from under $5,000 to over $15,000 dependent on what you choose.
You will find that boats are a very nice hole to pour your money into. The most important thing is that you find a hole(boat) you really like before you start pouring, because you are most likely not going to get much of it back when and if you sell.
Whatever you do: HAVE IT SURVEYED!!!!!!
Unless it is obvious to you that the tartan mast shows signs of corrosion, or the standing rigging has problems in any of the boats, have them surveyed.
Here you have a simple proceeding to find yourself if the boat has problems on the mast or on the running rigging. If in doubt look for a surveyor:
BoatUS.com - Seaworthy Magazine
Sailboat Rig Problems - J. Stormer
And how about the engine? The tartan has still the old one?