A gentleman named George Carney a number of years back came up with a formula for ballparking engine size vs weight. This was well before the urge to overpower everything twice over. It will estimate an engine size that is not too small, nor too large. For a 2 stroke engine multiply the weight of your plane by .07 to get around .070 cubic inches in your case. If using a four stroke, multiply the 2 stroke size engine by 1.5 This again would roughly be a 1.00 in your case. It wouldn't hurt for me to know the design and intended type of flying for the plane and the wing area to get a wing loading figure. Take care and let me know_Bob