I did it and I'm not a mechanic. My neighbor showed me the way and the idea came from 4onthefloor, a member here. I used a 4" x 5" piece of 5/16" flatbar. Measured and marked with a chalk pencil, cut it with a hack saw, and grinded the corners with my bench grinder to match the curves of the stock intake. Tapped and drilled for fittings, and plumbed with brake line. Here's the part tha came from 4onthefloor - I'm utilizing a water pump and bypass thermostat housing from a 261 to route the water through the intake. Here are pics.
http://community.webshots.com/photo/360111285/1360112009071636143ahASoZ As you can see, I also had to grind the bottom of the plate to allow for header clearance. All of this and I'm not sure what your options are for a 250. I'm sure others will chime in. BTW Most of the year here in the NW - we need the intake heat!
