273 adjustable with roller cam?

I'm not arguing about it, but what do you think racers ran back before roller rockers were available? You bet the stock 273 rockers have seen .650 lift. Probably didn't endure it real long. But rest assured races were won with them. Just go back and read crackedback's post. There's your gospel right there. Although I would add I wouldn't be afraid to run them on a .550 lift roller. I think they'd hold up good. Specially if you have them bushed.