I'm wondering what all I need (and how easy it is) to replace my oem handlebars to Dirt style straight bars on my '94 F2 fighter project. Here's how she sits now:

 

i'm wondering the same thing, I want to put some mx risers on my F2. the top triple plate is too thin, from the looks of it, to simply bolt some clamps on.
maybe a billet aluminum top clamp that has some thickness would work to drill/mount bar clamps.

I would imagine there are aftermarket bolt on kits that would allow for either 7/8 or oversize mx style bars. I havent come across any yet, though.

 

if you look at a late model CR 250, the top triple has holes in them and the bar clamps bolt to the triple.
that might be a good place to start looking, there are also risers/adapters for oversized bars. On my RM 250, the top triple has the bar clapms integrated right on it. I have a set of oversized bars on it now with these adapters.

I'll get some pics of mine later if you want to see the adapters, you'll have to search for the CR clamps