Two points - the early Tartans (34 and 27) were well constructed, but have no relationship to the newer models that fetch deserved premiums on the market. From that perspective, the early Tartans deserve no distinction from similar vintage boats like the Pearson 33 or 35 or Cal 33 or 34. A recent Tartan 3500 may be worth three times as much as a recent Pearson 36-2, but the earlier boats from these builders in my opinion are somewhat interchangeable. So if you stay in this size/price window, you night want to look at the others also.
Secondly, you''d better not be in a rush to get anywhere because these boats are relativley slow. The Tartan 34 rates 174 in PHRF-NE, three seconds slower than the Tartan 30. From my personal observations, the Tartan 34 doesn''t sail to that rating, especially upwind.
My personal preferance would be the Cals of that era, as having more room and performance.