Built the Sig Miniplane years ago. Hope this isn't your 1st kit. If it's your 1st bi-plane, one of the most important aspects is wing incidence. Makes all the difference between a nice easy flyer and a handful with lots of constant triming! Those cabane struts can be a little tricky to get the correct upper wing incidence angle.
As I recall, mine was powered with an old Fox .45 schnuerle. Very snappy aerobatic performer. Easy flyer though. Mine was a little heavy. Covered with silk and dope and painted with K&B Superpoxy. I guess that shows my age! Seems to me, it did require a couple ounces of weight in the nose.
One thing I do remember was I couldn't keep the wheel pants on. Also the fairing on the landing gear kept cracking. Finally did away with both. Nice little bipe though. Good Luck!

John