everyone recomends the #10, but I'd get something that doesn't defuel on the big end... like he said, you're gonna need to address the transmission if you plan on doing a plate and injectors...
something like a #4 or #6 will keep the torque from hitting so hard down low, but won't defuel as hard as the #10 up top.
*I* would just break out the grinder on the stock plate... something like a #100 plate, and position it as necessary to save the transmission (do that with any plate you get obviously)
if you want some smoke and some more power on a budget, slide the stock plate all the way forward, slide the AFC housing all the way forward, and remove the AFC spring