Midwest Pitts Super stinker 27% scale

[noseheavy]

Hello everybody and greetings from Norway.
I am currently refinishing a Mw Superstinker 27% and i have trouble to get it to ballance right.I am using a Supertigre 3000.I used to have the blueprints lying around,but as the complete idiot i am,i gave them away..I have been told that CG is located 3,5 cm behind the leading edge of the lower wing but i am not sure of this.Would also like to know if the plane should keep nose level at CG or point nose slightly downwards.
I thought i got it right and took off for a test flight last week.Found out in flight that the plane was noseheavy and impossible to land at low speed,ripping off the main gear and parts of the underside of the fuselage as result..Dont want to go there again.
Hope anyone can help.
Best regards