At what point do stock stamped rocker become a risk?

Well, I'm going to be putting my 360 in my 70. These are it's specs as it sits right now:

Stock replacement cast pistons .030
Summit cam .420 int .441 exh 262/272 advertised duration (matched springs also) this cam is in straight up
360 "J" heads, stock ports, stock valves
factory 4bbl dual plane intake

I had rebuilt this motor a while back for my truck, broke the rings in wrong, so it uses oil, gonna need a re-ring at least, only has about 40K on the machine work. Dart is a street/strip ride, 727 with 3000 stall (if I don't go stick), with 4.10's and a detroit locker. Sitting on 28" tall street tires right now, I want to get some 26" tall MT drag radials. No power steering or A/C parts on the car, I have no idea what it weighs. I was running desktop dyno and it looks like I'd gain more from getting the heads ported then a cam change at this point. Course I still have to get the engine in the car, and I haven't finished the engine bay yet.