First off, be careful not running a battery. The battery helps dampen any voltage spikes that may occur and also keeps voltage right up there. Just this passed weekend I experimented with a "battery eliminator" of my own and the results were pretty good. I ran it on an MC21 and it worked fine.

You may find your "battery-less" setup difficult to start and the RC valve will function slowly at lower rpm. Not good.

I still think that you should go with the total loss setup. It's hp for nothing. Just costs you a little in time keeping the battery charged. Or fit an RS250 (NF5) ignition.

When you say not to run the power jets, are you referring to the air solenoids? They control airflow (via MAJ) to emulsion tubes. You're running big carbs, so just disconnect them. It'll make no difference.

Don't worry about wiring in the GPS to select different maps. Just hard wire it to 3rd gear and forget about it. The most important thing is that you do the wire splice (Or/Bu to 12V). If you need to alter ignition timing then make up some offset woodruff keys, or get yourself a selection of flywheels. MC21 is most advanced, then 18 then 28. Then go out and play.