the mount i used, i can't recall the brand, but it has 4046L cast into the top of the base. the base is round and the arms are radiused on the sides and the bottom of the arms are tapered ....taller at the base to narrow at the front. i drilled holes all the way through the arms for the engine bolts and then spot milled the areas at each hole parrallel to the topsto makea seat for the nuts. i guess i never gave the cowl a thought, though, my cowl breaks at the firewall and comes completely off exposing the entire engine. working on the engine area is much easier that way.