You can do it with a stock block, but I would get an R-3 for the ability to get a bigger bore and longevity sake. Plus, an R-3 will allow you to add serious steam down the road if you choose.

Do it N/A. WAAAAAAAY more impressive than a power adder.

If your car works and with the correct gear and converter, 625-650 should get it done in good air and still be plenty driveable.