With the gearing that you list, running the F298 shouldn't be a problem. It idles at about 750 rpms with a definite lope. I have one in my 261.
Considering the poor ratio between the intake and exhaust flow, I would think that a split pattern cam with more duration on the exhaust might be the better way to go, but I haven't tried it.
I had no problem bending the Clifford moly pushrod once on a stuck valve.
I can't confirm, but I would think that the moly ones are just lighter than the others, since moly is stronger than steel per a given thickness.
