I'm like the rest of you and the best I came up with is to go to an exhaust shop and have the pipe bent for the hoops and weld two ends to flat plates that we can mount to the top seat belt mounting position and have the two middle ends of the hoops and weld them together using a flat piece of steel or use one piece of flat steel to go from one side to the other and weld the hoops on that then have it powder coated or plated, mount it and we have it but I have yet to get this done but it is an idea
they also have a red c4 on the barret jackson site, I think its car 65 but not for sure and it looks like gm is offering the car and it has a c5 convertible type deck lid with what looks to be a waterfall. I tried to get better look at the car but what comes up on the site is what you get from what I can tell
Look on ebay I'v seen them listed over the last few weeks, sorry I can't remember who was offering them. The seller had them for both convertables and coupes. Price was around $300.00 from what I remember. search "C4 corvette rollbar".