You can get drill bits for stainless from McMaster. I had a job at work a few years back that required drilled about 1000 holes through stainless 1 x 2 rectangular tube, the bits from McMaster did the trick. I think I went through 3 of them.Sure. Although I'd probably use stainless steel ones. The bigger problem is drilling holes in the stainless steel for rivets and such. You might as well throw the drill bit away after each hole, they'll go dull that fast. Cutting stainless is an issue, too. The shrouds have to over hang the top tank of the rad. The tank sticks out about 3/8"-1/2" from the fins. I'd like to have the shroud snug up against the cooling fins. I plan on putting door edge molding on the edge of the shroud that will touch the fins to dampen vibration. If I do it this way, I'll have to cut notches or a 3/8"-1/2" thick strip out of the top of the shroud. Forget trying to use a hack saw, I use an angle grinder with a cut off wheel.
I just took 15 minutes to size things up. I'll work on this project this weekend. First I want to wrap up the fuel pump hook up and hose routing.