999 ?

I asked a question about 999/ 727 swap and found out that I need to stay with the 999. I built my spare 999 with stock parts.

Now on with the question, are there better parts for the 999?

My local parts dealer told me at first that no parts were available then I talked to a tranny guy who said he thought that 904 and 999 were the same, so back to the parts place and wa-lah!
I didn't even ask about upgrades at this point!
I plan on building the 999 that I'm swaping out. I've got time (Ha Ha) so I want to make any improvements I can.