Paul, as this video of Bou messing around on an Africa Twin shows, he doesn't even need a real trials bike to do a lot of stuff:
https://www.youtube.com/watch?v=yPLJn3IygAgI hear you on carbs, I don't like them and I am not sensitive enough to do a good job of tuning them. Rod length, porting, engine building and all that kind of thing are interesting to me and there's a lot of material around that you can read to get a better idea of the how and why of them. David Vizard has some very good books and a YT channel and I'd recommend him to you.
The Savage is so mild that I can fiddle with improving the power without violating my "no more race engines" vow.

While it is nice to know the rod length, I'm not going to be ordering a custom rod from Carrillo for a street bike project that will see minimal riding every year. It sounds like the stock rod is plenty strong enough if the RPM is held to a reasonable maximum, and getting enough extra length in the rod to make a significant difference is probably not going to be cost effective, even for the typical "it is my bike project, who cares about the budget?" scenario.
cheers,
Michael