What you describe sounds typical. Still, I would verify the motors condition with a compression test.

Some low end can be picked up by milling the head .030" and a bit of port cleanup. Not a huge gain but combined with a valve job, it helps.

I went with a turbo.

Kevin

87 Turbo Intercooled Raider, roller cam, torsen rear diff, LSD front diff, lockup auto with modified converter, V6 brakes, low transfer case gears...