The best (for you) first gear ratio in an M20 is 2.56:1 in a 63-65 unit, or 2.52:1 in a 66-74 unit. This is about 1/2 way between 2nd and 3rd in the SM465 you replaced.
What you've done is you changed your starting ratio from 13.35:1 (2nd in the SM465) to 5.86:1!!! I'm not surprised you're unhappy! If you switch your rear gears to 3.08, you'll have a starting ratio of 7.05:1 which is better, but I'm guessing it will still suck. Of course, 3.73 gears will get you back to 8.5:1 starting -- better, but your highway mileage will be exactly the same.
I don't think there IS a cheap transmission swap (except back to the SM465) that's going to work well with your 2.29:1 rear. Interestingly enough, the 2.29 rear end makes the granny first in the SM465 come out to 15.23:1 -- almost exactly where your second was! That would actually work out pretty sweet for ya!
Brian
