same place as on a cr125,downstream of the reed cage on the side that your pump is going to be on.Whatever happened to your CRF250 kart from a few years ago? You sure did a nice job on it,the pics of it looked great.(I think it was yours?)
There!!! By far the best place. Drill and tap for an 8mm Time-Sert into the redundant gallery and cross drill into the crank chamber. Then bolt in an 8mm pulse nipple, or you can use a banjo union if desired.