My guess is you need a 289 for a vintage racing class. The easiest way to do it with a guarantee is to buy one already built.
Cobra Automotive probably has the most experience building race prepped 289s.
Otherwise, you can spend up to $15k with no guarantees your combination will work. To build that kind of power means you have to check tolerances with everything. You could spend $1,000 just on micrometers and tools to make sure you build is flawless.
I'll add to 69fb00GT a lightweight knife-edged steel crank and lightweight valvetrain (titanium if available). Basically keep everything that moves as light as possible. You get the idea.
Also, if you have to bore the block, keep it a .010 to .020. You will want to retain as much strength in the cylinder walls as possible at such high RPMs. You will also need a zero deck height and shaved heads and/or domed pistons to get the high compression you will need.
Here is a quick build sheet
Race Prep Block and rotating assembly: $1,250
Lightened Steel Crank: $1,500
CP Custom Forged Pistons: $1,000
Carrillo H-Beam Forged Rods: $1,600
Custom Heads (Victor Jr. Minimum): $2,000+
Custom Cam and Valvetrain (Mechanical, Titanium Valves): $1,500
Oil System and Cooler: $750
Radiator and Cooling: $750
Aluminum Flywheel and Driveshaft: $750
Intake and Carb: $1,000+
Fuel System: $500+
13.5:1 - 15:1 Compression Ratio
7,500 - 8,000 RPM Range
Definitely need a drivetrain to support!
Definitely need big brakes to stop!
$0.02