Torque convertor vs turbo lag question

A 2400 Stall should help with the Lag some. With a 383 CI motor and 1 GT45 you will have instant boost most likely with out using the converter to get it there. One thing that will more than likely happen is you will run out of Compressor Wheel on the top end. 1 of these is too small for your application in my opionin. If you are going to run only 1 Turbo you may think about using this one instead. Same Family as the GT45, I know a guy running 2 of these on a 410CI SBM that is making over 1250 HP to the Wheels.

http://www.ebay.com/itm/gt4292-gt42...es&vxp=mtr&hash=item3a6bf66aef#ht_5697wt_1183