what des it take to stroke a 360 to 408?

Ok, so this build is a 360, with correctly sized pistons... That leaves the rest of the combo. I think the cam is a problem and from what you describe the valvetrain is probably appalling. I would start with the heads because the geometry on a Mopar is all determined by the valve job. I don't think if your shop did what you decribe in terms of setting up the valvetrain they should be used for anything further. I'd find a competent performance shop to check them out and fix what they inevitably will find. Replace the cam. The XE268 is a good choice in general but the XE274H would have been my first choice for a 360. Once you have the heads done and the cam ready, then get a set of checking pushrods and measure for the right length pushrods, and you're good to go. This engine should be able to do what you want for a little more investment. If you want to go bigger you can by all means, but you're basically planning to build an entire new engine when you talk overall cost.