Can anyone tell me if the gold Crane roller rockers will fit under stock bbc valve covers w/640 lift cam?

No. Crane golds require a longer stud.

Talk to FelPro - I think they make a double-thickness V-C gasket that might give you enough clearance. I used a set on mine, and it gave me just enough clearance for a set of Comp Cams full roller rockers with poly-locks. Valve covers were not stock, but they were not the tall ones either. About all you can do is assemble the valvetrain and check for clearance. I think we had to machine a little bit of material from two of the rockers because of interference with the valve cover near the indentation for the valve cover bolts. Pay particular attention to this area.

They use them on HP 500 motors. The oil drip tabs need to be removed. I know my stock valve covers would not work with Merlin heads.

just but a set of imco or b&m covers and forget fiddling with them.

what roller rockers will work in a mark IV 7.4??? Is it even worth adding them? I am re-intstallign my b&m 174 blower so i figured i might do roller rcoker while she is apart

I have the same rocker covers, and use Comp cams SS rockers. They required longer studs and this put the polylocks on the exhaust in contact with the covers. I didn"t know this at first, but noticed my engine builder had used double gaskets. Since I did not want double gaskets that might leak, the solution was to turn the polylocks on the lathe to make them shorter.

Hardin also makes a 2 piece valve cover for that exact reason

here is a picture of the hp500 rockers look closely and you will see that one had to be modified. If you want a picture of the inside of the cover let me know. They use standard oring style gaskets.

Like Scott said, I think its the intake rocker on #1 and #8 that need to be modified. Can verify when I get home.