This is such a great forum - thanks everyone for all the informative replies!
OK, It's clear as to what I'll be taking to the machine shop. I haven't bought the "Prothe" pistons yet as I'm still not sure if the next size will clean the scratched bore on #4. I think the next size up will, but I'm not the guy boring it. That means I will need to take it to the machinist, get his professional opinion (as to the bore required to clean up), order the pistons and then hand them to him with a page from the Bentley, and make very clear that he needs to hold the .001" spec over the piston diameter.
It cost me 20.00 to machine the end of the crank for the D sproket. You may not find a machinist that cheap, but IMHO you are an idiot if you could get it done for under 100.00 and don't. Even if you are running Vbelts, the added security is worth it.
Top of the page, see the FAQ link. Look for serp setup.
As to my crank nose (man some of those threads in the FAQ on serp belts, alternator clutch pulleys, etc. got real warm

).
It may sound crazy (yes, I could be an idiot) but I'm leaning to just getting a new stretch bolt and properly installing the stock set-up. Firstly, the v-belt is much more forgiving than the serp (if it's not over-tightened). Plus, the current fit of the key-way is like brand new - no wobble whatsoever.
Personally, the one-way clutch is something I will stay clear of as I have had several similar devices let me down. Generally they work well in principal but are just not robust enough for this type of application. The door isn't closed yet on this "D" sprocket as I'm a fer piece off from putting belts on, but that's where I'm standing today.
The machining of the crank is a non-issue as I have a sweet Lagun mill about ten feet from me now. Maybe I'll just do the sprocket and not all the other stuff. Theman53 - any links or some direction as to the bolt on "D" style sprocket?
Thanks again everyone.