What about finding the proper bracket for your truck? It might be a little hard but fabricating would be a lot harder.
GM allready drilled the holes for you, you might as well use them. If you look on your crossmember (passenger side) you'll see the two holes where the V-8 and lil'6s bracket is bolted on, there should be another hole a few inches in front of those where the front bolt of the 292's bracket bolts on.
Now all you have to do is find the proper bracket, because unfortunatly this was unique to the 292. I'd check out the local junk yards, ask for places that have old chevy trucks siting around. Anything from 63 on with an origanal 292 will do you. You could also place want adds on the clasifieds here or on chevy websites.
I feel for you, I was lucky enough to get the brackets and everything else when I upgraded from the stock 230 to a 292 on my 63 chevy.
