I would not think the 150 would be too much, especially with roller furling. I have a genoa, but since I bought it used, I don't really know what size it is - I'd guess 130 to 150.
On mine, the prev owner or more likely rigger attached two pairs of stainless straps to get the furler drum above the anchor locker. One pair is about half the length from the chain plate up to the deck, and the two straps (about an inch wide, maybe 1.5) straddle the chain plate, with a clevis pin and cotter pin attaching these to the chain plate. Think of a sandwich, with the chain plate the "meat." These are bolted to each side of another pair of straps with a pair of stainless bolts and friction nuts. I suppose you could use one longer set of straps; I don't know why they did it this way, other than maybe they only had shorter lengths of strap in stock. The lower end of the drum attaches to the upper straps. I think there's an extra set of toggles, I can't recall, but that would depend on the way the furler you buy works.