Don T - I see some messages for you that confuse the situation. If your 125 is not starting and you have verified you have a good ground on the Point Saver - then I suggest you remove the Point Saver and return to an original points, condensor, coil, spark plug set up, then reset the timing and see if it runs again. Assuming it runs and timing is correct, then you should be able to re-install the Point Saver (following David Kirk's specific instructions) and the timing will still be set correct, and the 125 should start and run.
Bill J - I checked FAQ #23 and it's titled "Could you tell me some things I can learn from a dog". I hadn't read that one for quite some time. I believe Ranger Buck was the author - it's from back in the ole days of the Forum BGC.
Now, I think you were really referencing Charlie's FAQ #23 (give credit where credit is due) - yes, IH made a couple different versions of the ISO-rails. Why, I don't know. As far as I know the black ones shown in the FAQ pic may be "CCC" not IH, and I think they were designed for the 1282 (12hp K Kohler), and maybe some later units that might have used a K series single cylinder but not certain. You must have noticed the rear cross brace has to be cut off/out of the black version.
With regard to the knotch - I believe you're talking about the little square cut-out off the top corner. Who knows why, but it does appear having it there would allow you to possible drop the engine into place with the ISO bars already installed to the engine - if you have a chain hoist you are using to drop the engine into place so you could still get the ISO-mounts installed correctly.
Did you happen to notice the "oblong" holes toward the rear of the black ISO-bars? Some of the original ISO-bars had the oblong holes - which is for the rear bolt to mount the engine to the ISO-bars. The engine is "just a tad" easier to install with this oblong hole, but the front holes still require perfect alignment.
Now - as far as the snubbers, the early version were teh U style as you noted, which I believe is more proper for the way the ISO-bar aligns to the frame where the snugger rubs. The square shoulder snubber is the current replacement, and just wears on the edge - I don't know how you measure the "gap" required by the Service Manual - when it's just that little edge tip. I suspect no one actually measures and shims their snubbers any more - even tho the idea was to not allow the PTO belt tension to pull the engine to far down thereby smashing/squishing the ISO-mounts.
I would have thought by now you had determined that 1650 must be a keeper. It does no good to keep track of how much money you put into it. If that begins to bother you it's best to just grab your 109, and get some seat time and Kohler K fumes to relieve your tension - and then get back to determining other ways you can spend more money on your 1650.
Charlie - if "Off Topic Monday" now a fully sanctioned day of the week? (I didn't really notice anything I could say was off topic but may have missed something). Still hoping Kraig could assist in getting some pics downsized and posted.