Gearing and forums - a match made in heaven. Ask a racing cyclist about gearing and have your eyes opened. It counts for a LOT when you're limited to two legs. There is no single 'right' gearing, why is why the pedal boys have 18-21 of them and even the have to change from close to wide ratio blocks between and high and low speed rings depending on terrain.
You cannot avoid compromise, there is no perfect option, you just choose what's your priority 'zone' and accept the rest of the package deal that comes along with your choice. When I raced motorcycles I geared to hit maximum revs in top just before the braking point on the longest straight - that was about the nearest to a true 'best' choice, but even then sometimes it screwed you for revs between two corners and it could be better to avoid a time-wasting gear change on a slower part of the track and not get the perfect revs on the straightaway - it all depends. I think the UK/Euro 3.31 gearing was all-round best for open road driving and 3.54 a touch low with 15" wheels. Yet 3.54 was only a mid-range diff option for D-types on huge 16" tires and they went as low as 4.10 or even lower.
Just for grins, here are the stats for the D I'm building which will have the correct later 6.50x16" rears. The gearbox is 4-speed dog box with these ratios: 1st 1.88; 2nd 1.208; 3rd 1.0 and 4th 0.77.
So first is around second on an E and a supposedly 'low' 3.54 diff will give the following gear speeds at a conservative 5500 rpm (which will be routinely exceeded in the intermediate gears):
1st gear max 70 mph
2nd " " 110
3rd " " 134
4th " " 171
A 3.31 diff would give maximum speeds in the gears of 76, 118, 143 and 184 mph.
In the real world these are a bit on the high side, so I've fitted a 4.10 PowrLok into the solid axle. Even that stump-puller will give me 60 in first, 95 in second, 115 in 3rd and 147 in top. I'll settle for that during break-in :-)