Frankenboat factors;

The original 6.0na pinhead had a section of sail that went to the bottom of the mast.(you can do that with boomless rigs). With that removed and a samll amount off the leach you can build a nice squarehead and stay within the same sail area of 6.0na sail area. This is only a .995 hit. According to the tables Same Sail Area: within 5% of Calculated Approximate Sail Area .
You get nothin for downsizing the jib. Only if you remove it.
The other option(providing the self tacking jib is the same size as the 6.0 original) is rate as a 6.0 original with a larger main and take the .980 hit.
If you have a spin you take a .960 hit.
You also have to take a .995 hit for the selftacking jib. Does not matter if the size is the same it is a mod from the original one-design. See this section:

Other

Any other deviations from standard class configurations, including the addition of wings, can be assessed a penalty of at least 0.995. Multiple deviations may incur multiple penalties. Penalties may be greater than 0.995. Please identify any such modifications and penalties assigned and include with results reported to the handicap committee and Portsmouth Numbers Committee.