I have a setup almost like what you are building.
Hot rods welded 4mil long rod crank
Hjr 4mil dune port cylinders
21cc domes
Timing at +4
Vforce 4 reeds
Pwk28 carbs
Open airbox with pro flow filter
Barnett basket
Barnett clutch with HD springs
billit water pump
Pro circuit pipes
It has been an awesome performing and outstandingly reliable engine. It has a ton of hours on it, so i just rebuilt it, new clutch, etc etc. I would highly recommend going with a stroker build.
Once you have a 4 mil, if you decide you want more power and want a cub or serval, youll already have the crank!!