491 Big Block Chevy 635 horsepower on pump gas.
Dart 310 aluminum heads fully ported flow 408 cfm @.700 ,comp cams solid roller 244 @.050 .622 lift
short block has about 750 miles top end is fresh with only dyno time.
Asking $5000 without distributor and waterpump.
So a 420 with 14 deg RHS heads and shaft rockers is legal. I thought this was a budget class by those rules you just opened up the engine range to $18000 if somebody really wanted to win.
Even if the tire was illegal it would not have held up in court because the sampling procedure was not followed. Do the sampling procedure correctly and the lawyer wouldn't have much of a case.
To do it correctly you're looking at 7000 give or take a little for the long block minus intake and carb. That would be forged crank, H-beam rod, forged blower piston, hydraulic roller, dart pro-1 aluminum heads, block prep with splayed caps. I would build it as a 383 since the rotating assembly...
What is your project? No real info that an engine builder needs is given. What fuel, block, boost amount, heads, end use drag or street, and most important budget?