Do a 350. It will cost the same (or maybe less) and make way more power.
For serious power, you have two choices: T56 six speed or T5 5-speed, both of which fit an F-body since they were offered from the factory. A 94 and later T56 will take 450 lb-ft of torque pretty regularly. A T5 in stock form is only good for about 300-350 lb-ft, but aftermarket TKO T5s will take 500-600.
Either way, the tranny will take more power than your rear axle will. The tranny won't be the weak point.
