Your goal can easily be met. My 63 ran mid 11's with just a mild 440 and iron 906 heads. It weighs 3700 lbs and you can meet your goal of low 12's without going to a stroker. Course a mild stroker should get you in the 11's with no trouble. When I built my stroker I went with the 440 block and the 4.15 crank for 493 cubes. I stayed with the RB block in case I want to put a crossram on it later. I use the aluminum Indy EZ heads because they have good potential and keep the exh ports in stock location so the headers fit good. And they dont need offset rockers as you can use any 440 standard adjustable rockers. I also use a D-dished piston to keep my comp at a pump gas 10.6. And I built .046 quench in it. I dont use a roller as I just use a solid flat tappet cam. I was just looking to get in the 10's on pump thru the full exh and it runs that with no trouble and my 493 is by no means big bad race eng as I drive it on the street all the time as far as I like. And I wanted to be able to pull in any gas station to get gas. As was said I would stay with the chevy size rod journals and you wont have to do alot of clearenceing. Good luck , Ron