Best bang for the buck is a higher stall convertor. I like the 2800. It gives a nice jump off the line with those 3.23s.
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Do this FIRST and you will never regret it. Then install a semi-auto shift kit, and maybe your teener will bark the tires going into second.
With your planned mods, you're gonna have to do this anyway, as the factory stalls are just too low, and with any loss in cylinder pressure they will stall even lower, making taking-off an exercise in patience.
Before you take anything apart, do a compression test. Yur gonna need those numbers later after the mods are done, to help you chose a new convertor.