Was there a change in the water pump size

If every thing else looks like it will will work I would give it a try?What do you have to loose?

At some point in the 90's (1996 to be exact, I checked) Husaberg realized that the water pump was too small, and changed to a larger one. I had the same problem myself. I have a 91, and changed the head cause mine was a bit used. The new (used) head I got, from a 400, had a larger waterpump.

I too, also had the issues with the different rocker shafts, and eventually purchased the correct endplugs to fit. Hang on, I'm trying to remember......

I had my stock 350 head. I bought the new head, which did not have rockers. I had to reuse my rockers with the shaft that worked with them (10mm). But, the new head had endplugs that fit the larger 12mm shaft. I bought the new endplugs and was good to go.

I would not recommend using that configuration. Husabergs have always had a problem with cooling. They use a HUGE radiator to compensate for a sketchy impeller design. Also, some impellers have been known to dissintegrate, but if yours hasn't, I wouldn't worry.

If you have an active way to measure/observe your engine temperature, I would go ahead and use the larger rocker, otherwise, you will "void your warranty", as they say.

-Parsko

PS - You might be able to machine the other half of hte housing and use the larger one, but I haven't the slightest idea (offhand) if there is enough meat on the head to do this.