Extended high RPM

[another69]

I recently swapped gears in my car, and without overdrive the highway cruising is almost unbearable- the motor spins at 3000 RPM @ 60 MPH. I'm wondering if constant 3000 - 4000 RPM with my motor is ok until I get an OD? (3.50 rear gear)

Here are the basic specs:

GM 400 block (now 406) 2 bolt mains, Scat 9000 series cast crank/forged rods, speedpro hyper flattops, hyd. flat tappet 240/246 @ .050 cam, etc- shortblock built by a reputable shop.

Typical 350 trans w/ shiftkit, Denny's 1350 driveshaft, Strange 9"

Oil pressure, temp, etc are fine. I know that about 6000 RPM is max with my budget shortblock, but I'm wondering how close I can be to that on a constant basis.