Rear axle ratio opinion

Hi all. I was wondering if any one can advise me on rear axle ratio for my 67 Valiant 360. At the moment I am running a 3.23:1 ratio 4 pinion LSD and I was interested in lowering it to 3.50:1. Now for the cost on this change is it worth while doing it? Will it be significant on the performance of the car. The running gear is a 360 with Eddy heads, max rpm is about 5500 rpm and a Torqueflite 904 with a 3000 rpm stall with stock 14" wheels. The car is no heavier than 3200 Lbs.

Regards
Billy D...
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