70hp Yamaha info needed

[Jeffrey Pinney]

Need info on a 70hp,3-cyl.,2-stroke Yamaha engine. It is an inboard in a 12', SOS Express fiberglass jet-boat. Model# DD70D,code# 6M1,serial# 000436 on motor. Boat was made in 1990 in Florida. It has a Morita jet drive unit. I want to know more about motor and drive. Is this considered an inboard, or is it an outboard without cover, mounted to this drive unit? Is in excellent shape, BUT I want more power - better heads? Rebuild drive unit? Top speed about 30mph now - can anyone help with info? Thanks a lot