i run the same set up as your wanting. tfs stage 1 cam, 306, and p heads, with shortie mufflers, and a old single plane torker 289 intake, with 373 gears, and a 5 speed. i went 12.54 at 110mph with my motor, and shifted from 3rd to 5th gear, cause 4th gear was broke and wasnt there for me. thats the fastest run i've had, and it was my first time with slicks and front runners. before that tho, i had a best of 12.70, at 107 on 225, 255 16 inch rim street tires.
i highly recomend this motor.