Opinions on heads please?

DGC, my opinion is no, not without some serious port work on iron heads of any kind. The Magnums work great, but IMO, they are not the best choice here. The last 340 I did makes around 480 with Js on it. That's big valves, bowl work, cross section work, the whole deal. I did not flow them tho, so it's hard to say how good or bad they are empirically. I joke with my shop guys, that every set of heads I walk in with costs $800. It's not great, but to get the right results, the good machines demand good components. Any guide wear kills the seat quality, and that's 80% of the valve job's power right there. so now it's valves and guides..etc etc etc. In my experience, which is limited when talking about Magnums, these heads have consistently failed to perform on engines that were late model things, with blowers, and other stuff. Maybe it wasnt the heads, I dont know, but I wasnt impressed. I have been impressed by lower power engines running them tho. Under say 350 horse..Street engines. What I have seen is that it is very hard to improve on the stock Magnum port for low and mid range flow, and just as hard to get any higher lift flow and keep the great low lift numbers. It's still flowbench territory, because the tumble and swirl they create is easily trashed with a grinder. They are definately not my forte..lol On a side note, using any MP head should be approached in the same manner as Indy's...They are just as bad fit and finish wise, as Indy.