I have done this, and some choices will make it easier than others. First, the low deck 400 block is the only way to go because it will handle 150 to 200 more hp before it breaks, at about the 850 level after some use. Go with heads that have a stock port location on the exhaust to help with header clearance. fenderwell headers reduce steering turning radius too much for my taste. That is my reason for pushing the low deck/low port head combo, to gain the most clearance for headers. With the first set of headers I built I had to back up every time I got forced into the near lane at one track, couldn't make the turn. My solution was to cut out the floor pan behind the front wheels so I could move the pipes back for clearance, then weld in sheetmetal to box in the area by the tubes. That made for a nice foot rest! Once you get all the light weight parts on a 400 stroker, and move the battery to the back, your front/rear weight distribution will be acceptable, depending on tire size (slicks) and suspension. To help out starting line traction, gear it a little taller than you think it will need. If your expected trap rpm is above the shift point, drop to the next ratio, like from 4.56 down to 4.30 or 4.10. A torqueflite has the 2.45 low gear and with the torque of a big block it is extremely hard to hook if you build some serious torque into the motor. With the cost of strokers being about the same for different sizes, don't mess around, go with a 4.25 stroke and 4.375 bore for 512 cubes and be done with it. build the short block with a gas ported zero deck flat top, and you can run the Indy low exhaust port Max wedge port size EZ heads, and make 700 to 800 hp without breaking a sweat. The heads can be cut enough to make 13/1 compression with the flat tops, just be sure and have at least .040 piston to head clearance. If you want a solid 800 hp recipe, drop me a pm, and I will go over it with you.