Standard chevy frame mounts like those out of a monte carlo will work, as well as the stock small block clamshells, oldsmobile mounts will not work as they sit back farther on the frame and the engine block mount is different also or you could go with solid motor mounts and keep that power bolted down a little better. There are a lot of headers that are designed to bolt right in. I think jegs might have them listed or possibly summit. As for a crossmember nothing really special there just go with a double hump crossmember designed to bolt to a 350 trans. If you see that a company says for example "fits regal, monte carlo, grand prix, and cutlass (except supreme)" ive seen that a lot and have had no trouble putting anything in my supremes that a regal or anything else would fit