To even consider a mull design in the same breath as one from Olin Stephens is blasphemy!!!
First the wheel position...take a little getting used to, but I now much prefer it. Helmsman in front of those lounging about with an unobstructed view is a good thing.
Things to look for - possible deck delamination issues on the bow, forward of the coachroof. Have a look at the lower bearing where the rudder sits on the skeg. The CB pin can be an issue and you should ask if it has ever been replaced / repaired. If pin is original then I would use it as a bargaining tool, not a deal breaker. There is pleanty of repair info on the owers site to get you through doing the repair yourself. Design/function of the CB is verygood and easy to fix if needed. Beyond those you don't really have any issue other than the norm for a boat that age.
As for the question about era's of Tartans. I think the 'C' at the end of T34C clearly indicates a different era. It got that 'C' designation for a reason. (and not just because it's old)
I'd be happy to answer any specific questions you have if you want to PM me or post it here.
hunter Legend 37 Semper Paratus
Formerly - Tartan 34C Yawl