15hp race motors please teach me.

[Glenno]

Hi there,
I am very interested in learning all about the 15hp omc race motors.
I live in Australia and have lived race boats for a while.

1) What year models of Johnson- Evinrude 15hp motors are suited?
2) I have a 1989 model (picture below) but it seems to have an extra exhaust bulge just under the hood clip compared to the other race 15hp ones I have seen online.
3) there is no power pack on the side of the head like the normal 15hp omc, it's under the flywheel, I assume this can be changed back to a standard pulse coil an cd2 pack?
4) I would really like to get a race lower unit but don't know where to start looking.
Please teach me, I'm ready to learn!
Cheers,
Glenno