8 3/4 gears

To the original question, I'd go with the 3.91 gears. My recently put together "retirement Dart" with a 400 BB and a lot smaller cam than mentioned, a TF also from Mr. 1966, has 3.91 gears, aftermarket axels, and about 25 1/2" M&H radials. It does the 2800 rpm on Hwy 18 driving 60mph to the track, and seems just fine. Here on the west side of the mountains, with the traffic congestion we have, there seems few opportunities to do much driving at 70mph, unless you're a 100 plus miles or so from the big cities.

I wouldn't think a cam as big as mentioned would really be that happy at much less rpm anyway, and since it's a small block, all the more suited for the discussed gears. Heck, I've even considered going to the 4.30s; hey it's a LB 3.38" stock stroke crank motor, sort of like a small block with a gland condition.

Sure it goes through some gas, but it's pump gas, not Sonoco Blue, and I'm not commuting every day on I-5 to work in the Dart. Really how much are you going to be driving it going to shows and the track now and then? Plan on driving to Cali sometime, slap the 3.23s back in.