Kx250f fork setup

I'm going to be using a pair of 2009 kx250f forks on my next build, and I'm wondering what setup would be good on them. They came stock with .44kg springs I believe, but I'm not certain that's what they have now.
The oil spec is 5wt 319-415 cc.

This will be a Cr500r powered 120" or 129" build, and I weigh 165 with my BD suit on. I'm thinking about keeping stock springs and changing oil to 10wt and 400cc to start. Do you think I should get bigger springs too? Or instead?

THanks. Yeah I may have jumped the gun on this front end, because I assumed conversion bearings would be available which they are not it seems. So I'll have to either make my own spindle or somehow use the Cr500r spindle and press it into the kx bottom clamp. Or, I may just use an aluminum kx frame for this bike instead.

Opinions?