I am currently working toward the same goals - street legal, just around town cruising, and a mid to low 11 second time slip. In doing the math to go 11.50 at 3350lbs, it says I needed 400hp on the ground, so roughly 500 at the crank. A little browsing around here, and I stumbled across Fast68's, write-up on a 500hp 383. He made it look easy-cam, intake, carb, headers, an unported 906 and walla 500hp. Now, I know the devil is in the details but still at least hitting 450-475 should be doable and you know what it is. I found a 383 shortblock in good shape on the cheap. After talking with Fast68 and getting him to send me a cam, I threw on a Victor 383, a 750 Demon and some headers and it went 11.47/119 right off the trailer. I have played with intakes and carbs this past season and it now goes 11.30 in not so good air. To get the good time slips with it you will need the suspension dialed which you should be able to do with the Caltracs and a well matched converter (I've had good results with PTC). So if the bottom end of that 383 is in good shape it may be an option if you are around 3,500lbs, if it needs any work at the machine shop, then you are money ahead by going ahead with the 500+ cubic inch route.