Some thoughts:

To get the quickest acceleration out of the corners you need the lightest reciprocating assembly that is legal for your class, and that for sure isn't a stock 318 rod, which weighs IIRC 720 grams. A good weight to shoot for would be 600 grams. You also need the lightest pistons and pins, which aren't close to stockers or the old SpeedPro/TRW forgings. If class allows it, there are chevy rod/piston combinations that would work better and cost less.

Your mention of doing it the old fashioned way sounds like wishful thinking. There aren't any "old-timer's speed secrets" that have been forgotten due to the passage of time. The reason things are done the modern way is, the new ways are better. For example, back in the day everyone cross-drilled their cranks. Now no one does it for a couple of different reasons, and the new way is better. A lot of interesting things used to be done to pistons, but they were dropped because there was an easier and better wa.

There's a lot of material to remove from a 273 crank, although it is exactly the same as the late Poly/early LA 318. It's also the same forging as a 340 crank.

300cfm heads? Your proposed engine would have a very narrow power band.

I also don't believe that a stock 318 block will handle that amount of power for any length of time, but others may disagree. For 7000 - 9000 rpm hydraulic rollers are out, and what does the sanctioning body allow?

For ignition the sooner you can get away from a distributor and use a crank trigger the better.

Others may disagree about everything I've said here. I'm up to learning from others' experience.

This reply was an attempt to tether you so you don't go floating up into the great wide open. I've built a lot of engines in my head and many of them would have not worked and/or exploded if actually built and run to max power.

R.