You only need 500-700 watts in the Nexstar to fly very well. A 6.5 pound plane will fly on 5.5 pounds of thrust.

100 watts per pound is a rule of thumb for very good perfoamance with electrics. 75 watts per pounds is ok but not impressive.

The OS 46 that you are replacing does not really put out 1.6HP at any type of realistic RPM or resonable sized prop. If you read the fine print the 1.6hp is at 16K rpm with a small prop. Most sport engines are flown at 13K rpm or less.

Outrunners are normally flown at a maximum of 7-8K RPM. You will be on the low side at roughly 7200 RPM. Thus you will need to maximize thrust. Try some APC E props or Graupner mutiblade props with a high pitch.

The 4130 is not really a 1100 watt motor, especially on your battery. In order to get to 1100 watts on 5S you will need 60 amps. This motor does not like that type of loading except in a glider where the motor is run in short bursts and very little partial throttle time.

If you want to drag the tail, you need to mount the new mains so that the wheels are at the leading edge of the wing. Then add a tail wheel or at least a skid at the backend of the plane.

What is the pupose of this conversion? Trainer or electric test bed or both?

It were me, I would probaly get a 4120/18 to use with the 5s pack in the Nexstar then buy a 6S pack for the 4130/16 in the Cap.