A nice Rourke track bike in a medium size sold for £160 recently on the Bay of Thieves. It's worth much less in Hagrid size, so keep it and ride it. I love a track bike on the road, although fitting a generic road fork will lose the extra honking stiffness you get from round track fork blades. You may be able to find a track fork with brake clearance although steerer length will be problematic. I had Argos build me a new fork for my Harry Quinn. It was not cheap.