Well I have been searching this site and all over the internet for info on the CDI Mag Coils for my 35 Hp Briggs Engine.
To start with I am using it on a Mini Airboat with a 1.69 to 1 reduction and even though it is not a Mudmotor, you guys here seem to have done a lot of Mods on the Briggs and other V-Twin engines.
My Engine is a 613477-2112-J1, it is not a Marine Engine and I had no idea it had any form of Rev Limiting in the Ignition Coils. My engine was mfg in 2016 the replacement part number on the Arm Coils in the parts list is 845731 Cyl 2, 845308 Cyl 1.
I removed the governor inside the engine, using the 67" 3 Blade Razor-X Mini for the gov. While setting it up I noticed the engine coughed and sputtered at around 4200 rpm which I thought was odd as it was not near the rpm I should be having valve floating or bouncing. I didn't need to go over 4000 rpm with the engine so I did not let this bother me.
I purchased a used set of heads and sent them in to Peltier Engine Service, I had him do the head work including new valve guides and New Cam for Max performance at 4000 rpm. I bought a used PVT intake adapter from a member here and purchased a Mikuni TM38-86 carb, carb adapter boot, 1.8 float needle valve and remote choke set up. I did not go with the Mikuni 42 because I felt it may be more CFM then I would need within the 3800 - 4200 rpm range.
So after reading about the CDI coils and the 4250 and 4750 rpm limiter built into it I realized my shutting down at around the 4200 rpm was because of the limiter not the valves floating or bouncing.
Now I have seen on here it has been said that the 845731 and 845308 coils no longer have 4250 limiters, instead all those replacement coils are sent through with 4750 rpm limiters. On the other hand some have said it is not true. I ended up ordering 845601 and 845602 coils as they seem to be the ones coming through on engines with 4750 rpm limiter. I guess I will find out.
Thanks everyone here for all the information, great site Mud Motor Talk.

I forgot to update this, the coils 845601 and 845602 worked great they are the 4750 RPM.