Engine height

[Starling]

Hi,
I've currently done a partial restore on my 89' SF20 and it seems like I'm pushing a lot of RPMs for cruising on plane. I'm fairly new to boating and have used a newer boat with a flat back that got on plane and stayed there at much lower RPMs than this one. I know that the Seacraft's have no flat back but the motor seems to be using more RPMs than I expect. Right now I have about 50 gallons of fuel, a T-Top, two batteries under the helm, 3 batteries in the fish box, and it's about 4800 cruise at 20-22mph. Is that normal? My prop is a suzuki 3rx 14x16p. - Thanks