Any 1.20 Four stroker will do just fiine, you could order a fiberglass cowling, but I'll give you a little secret Get a 2 oz. or so fiberglass cloth, and after the cowling is put together, on the inside and brushing pure acetone, glue the fiberglass to the surface, apply a little bit of pressure with the brush, use an acid brush, they're short and stiff and cheap, in areas were the cowling is curved, cut the cloth in strips for easier placement, be careful not to brush too much acetone at once and ruin the plastic, nor apply so much at once that it runs all over the place, it will leave marks. You first apply the cloth and then brush the acetone over it, pressing it down, this reinforcement adds tremendous strength to plastic parts, it can also be used inside wheelpants. When painting the cowling later, spray a little bit inside too.
It is important the way the cowling attaches to the fuselage, I've found out that having the hardwood blocks touch the plastic is best, position the cowling, drill the holes, remove the cowling, enlarge the holes in the hardwood mounting blocks and insert a 4/40 T nut to screw the bolts into. Enlarge the holes on the cowling just enough so you can pass a short piece of fuel tubing (silicone), for each bolt cut about 1/8 long piece of tubing, insert the bolt through it and then attach through the cowl, you must use a small flat washer with each bolt, to stop the tubing from sliding out of the hole, this way the cowling material is not under direct pressure, and the bolts do not have to be tightened down all the way, no cracked cowling.
And all you asked was if the cowling should be trashed?