Converting XR100R forks and front brakes

[Redbullrider111]

I am wanting to convert my girlfriends 01 Honda XR100R to inverted style front forks such as what comes on a CR80 or CRF150R. I was wondering if anybody knows what will bolt up to the XR's steering head, weither i have to use the XR head bearings or the CR or CRF's. and obviously i would use the CR or CRF front wheel and disk brake and just mount that up like a normal front brake system on modern bikes. i'm also thinking of getting the BBR 120 big bore kit($260 ebay), comes as a full kit with cylinder, high compression piston, cam, rocker arms, valve springs, and top end gasket kit, also lookin at a rev box and a FMF powercore full exhaust($170). the reason i'm wanting to do all this is because she wants a little more power but is afraid to step up to a CRF150R cuz she thinks is gonna be too big, money is an issue too. but i figure with around $600 in upgrades and mods will turn her XR into a rather good handeling and more powerful bike to suit her.

[Redbullrider111]

or would it be cheaper to find a used CR85RB and just swap out the motor so i'll have better suspension all around not to mention disc brakes both front and rear and basically a cooler race setup