Ok, I've got pics now and I will attempt to describe what I did to make it work. Keep in mind, my way is just that. There are multiple ways to do this, but this one made the most sense to me.
This can be done with your stock footpeg mounts (or another set if you don't want to destroy your only set).
If you take a look at the mounting plate for your stock pegs, you will begin to see what I did by comparing them to the pics in the link. First, you need to disassemble the footpegs so you have only the mounting plate remaining. Now, remove (torch, grinder, whatever) the block that the peg pin mounts in to attach the footpegs. This should leave you with a flat plate of steel with 3 holes in it...2 round and 1 oblong. At this point, I filled in the oblong hole with my welder to give me a solid lower plate. As you can see in the pics, I then aligned the FRONT bolt hole of the plate with the REAR bolt hole of the new footpegs. This is easy enough to do right on the trike so you know the alignment is right. Now, I simply adjusted the pegs to make sure they were flat and level and then clamped the front of the footpeg to the plate. Then pull the entire assembly back off the bike and weld solidly together.
Voila! New TRX450R footpegs on your classic 250R. As you can see, only one bolt actually goes thru the footpeg AND the plate. The rear bolt only goes thru the plate. You might question if this is solid enough to hold up, but I can tell you they will if your welding is good. My first ride on them was at Wellsville the day after I fabbed and mounted them and they came thru with flying colors. There is also a very slight position change, but it's minor. A little higher and a little back is the sense I get, but not more than a quarter inch in either direction.
Please feel free to ask any other questions you might have about this project.
Link for pics...
http://s59.photobucket.com/albums/g3...sumerlin/mods/