cam/intake manifold matching ?'s

[200k5oh]

A freind of mine has a 90 LX.

a quik rundown on his setup:
AOD with shift kit, stock torque converter, stock gear, Offroad H, MAC unequal length headers, and FMS roller rockers (not sure what size they are they were on car when purchased)

he purchased a crane cam, .498 lift, the Econo cam i think its called.
He is having it installed, he still has the stock e7's with a stock upper and lower intake.
Now wont that throw the power band way off? being that the intake is built for hp up to 5,000RPM ish? and this cam i think is up to 6500? hes not really a car savvy kid, he just wants his car to "cam over".
and also wont it not be good for that camshaft to not have a stall converter? i think the range on the cam is 2300-6500.

also one more question...is their a way to tell what size rocker arms he has? is their any marking on them or something?

thanks.