Could always just throw a 2.76 gear in it and roll! Honestly, that's likely what I would do if I were to put that many miles on the car even with the OD. 75mph at 1800RPM, yes please.
Even with my A833OD, a 2.76 is still 2000@75. Not that 2K is a bad RPM to cruise at, there's were I run right now with 3.21's and 65 mph. I could drop even further to a 2.45 and hit 1750@75, but I'm not sure the clutch would last with a starting ratio of 7.57:1.
At the same time, a wide ratio T56 with 3.71 gears and 275/40R18 tires is 1750@75 and 1500@65 and still has a starting ratio of 11.02:1 while an A833OD/2.76 combo is 8.53:1.