You may be able to drop some rpms by running a little taller tires. Looking at the number cruncher I'm getting that you're running about 29 inch diameter tires. Going to a 31 inch diameter will bring your rpm's from 2,900 down to around 2,700,without any other changes. That appears to be about the best you can do without doing some tranny or rear end changing.
Speed


1954 GMC 350
1957 GMC 1/2 ton
1962 Chevy C-30
1952 Chevy 6400 dump bed project truck
'98 Harley FLSTC
'66 Pontiac Catalina
'76 Chevy 1 ton Duallie
'84 Bronco II
'78 Dodge W-200
'81 Toyota 4X4 truck