Currently, my 1940 home has old steel gutters attached by straps nailed to the roof shealthing. I am replacing the roof and the gutters, and would rather go another route in connecting the gutters (the shingles are popping up where the straps were installed). There is no fascia, only a decorative crown molding on the underside. Is installing a fascia board the only other option? What would be the minimum size of fascia needed? I would like to keep the crown molding, but concerned that installing fascia board would look odd and block the view of the molding. I have attached a picture...

thanks in advance!

PS I am also cross posting on home repair too...