Well a decent .61 2 stroke is a great place to start. A light weight .91stroke more than you'll ever need. A 1.20 4 stroke simple to heavy...forget it a decent .91 far better instead.
Most of us and there are many thousands whove enjoyes tigers have increased the rudder aera /just make a bigger one.
The wonderful thing with these aeroplanes is the possiblity of placing the CG a long, long way back before things get anyway near critical.
This will cure all knife edge problem anyone is having.

Congratulations, you've got yourself a great flying aeroplane.