Gear change with w2 408

2.94 should be perfect for a 408, but maybe your cam and 28" tires are not a good match
I like 3.23's in a well tuned stock 340 with stock size tires and converter.Cruises nicely at lo rpm and blows the tires out easily at lo speeds. Going to try 2.94's...I tried and did not like 3.9's and 3.5's
Gearing with the 4 speed has less tolerance to under gearing than with automatic, since there is no convertor to multiply the torque and absorb ignition pulses at low rpm. Another factor in my case is the the lightweight flywheel, if I recall correctly mine is 16lbs, rather than the normal around 30lb unit. Many people seem to like the 2.94 gear coupled with an automatic, for my car the 3.23 just feel right. The engine is "in the zone" on the road at 2700-3200 rpm.