i personally wouldn't use them if this is a specialty car - meaning one that you want to save. Caps do restore structural strength - but they are not as strong, nor do they stop the corrosion under/inside them. If this is a driver then go for it, but in my experience (especially in the northeast where rust is now the biggest issue) they are a stop-gap measure at best. I've found it better if the repair is to be permanent to simply repair the affected area either by fabbing repair parts or using repro parts and sectioning them in place to minimize the impact.