Best tire with 3.91`s

I'd only caution that you need to gear for the rpm you want but not by using the trap rpm you're curently getting. If that makes sense...lol
There is always a certain amount of slippage in a convertor. You dont want a lot but there will be some. So if you mathematically need say, 4.30s to trap in 3rd at 5800, you may find that with 4.30s you're trapping at 6100 because the convertor's slipping too much. If you go down in gear with the thought of reducing the trap rpm you'll be hobbling the package for the sake of a slipping convertor. And slippage does change with gear changes... Generally the lower numerically the gear, and the larger the diameter of the convertor, the more slippage you'll have in 3rd.