Just ordered the Dago Red built by World Models. Now the fun part, which engine to put in it? Stick with a 4 cycle 70, or go up to a YS 91 or Saito 100?

I have a Futaba 9C, should I purchase the Futaba S136 retract servo, or go with another manufacturer?

What advice do the seasoned fliers have to say?

Thanks,

Ron