Just kinda seems to me the big bore short stroke combination would work. You don't need torque to "get off the line". Once it's wound up, it needs to stay wound up. A modded 358 inch R5P7 deal could maybe fill the bill. Seems like parts are around yet for them. Upper end of a budget, I would imagine. Any combo you decide on is gonna be upper end of a budget for the type of racing done.
All of it will be upper budget. I have no thoughts that a junkyard 360 with an Ebay GT45 or 2, will live. Could likely make close to the number, but for how long? The Gen 3 with a big turbo seems like the most budget friendly so far.