It really depends on the rest of the combo.
I like to put Second gear where I like it, and let the rest be what it will be. ....... Cuz for me, I'm almost always in that gear. My Combo like a Roadgear of 6.20 or better.
Roadgear is what I call the result of multiplying the trans gear by the rear gear.
But my 367 makes a lot of bottom end torque.
Lets say your 318 is an easy 10% down, then it will like 10% more roadgear. so 6.82. Remember this is for Second gear.
To get 6.82 you'd need 4.01s with the 1.70 gear or 4.58s for the 1.49.
However, if you had 4.01s with a 3.08 low, that would get you a 12.35 starter gear which is IMO, just plain crazy.
Therefore, you kindof have to accept that with this trans, second gear performance is never gunna happen with a 318.
If yur willing to accept that, then you can look to first gear.
In all likelihood your Duster was built as a cruiser and has 2.94s or less in the back. which would give you a nice starter gear of 9.05, and those 2.94s will cruise at about 65= 2400 ...... So you know; 2 out of 3 ain't so bad.
With 2.94s, 35mph will be ~2200, so you can't expect much performance in that gear. Until, at 55=~3400, which is a pretty good passing gear.
All in all, not so bad, if you just accept your baby for who she is. And besides, I just guessed at 2.94s; maybe the Duster has more than that, lol.
Did anyone mention tho, that you'll need a SBM K-member, 318 engine brackets, and a 318 throttle cable. a different fuel line, and if the car has P/S then you'll need pump brackets. The slanty cooling system might be iffy too. And as mentioned, the Duster needs a front-sump oilpan; and will likely need a T-bar upgrade. While the slanty bars will get the 318 back up to a decent ride height, with a bit of adjusting, Personally, I don't like the handling with those noodles. Since the K is gunna come down, this is the perfect time to swap in some big bars.
As far as swaps go, this is one of the easiest. But, with changing the oilpan and the K-member and the bars, the clutch and BH, and so on, it ain't just an afternoons work anymore.
BTW, the 10" V8 BH, Also requires a different Fork, z-bar, and so on, different from the 9.5 slanty.
IDK maybe the 9.5 bolts onto the 318 crank? I've never tried it.
Whatever you decide, FABO is here for ya.
