TC, if I remember, there are tubular A-arms for your 68 that are not too bad. A set of Q1 coil overs and a 4-bar setup would be low$ as well. While you are right, it will set you back about $1000 to $1500, it would be better than a stock '91 unless you did the same upgrades.
Disc brakes were available in '71 if I remember right. So you may have parts available.