First know whatever valve covers you run with the Offy or GM crossram you need to trim the the valve cover gasket rail lip off at the crossram base torque box or you will not be able to install/remove the covers after crossram is installed. After removing the valve cover gasket retaining lips near torque box you will need to use 3M super weatherstrip adhesive to secure the gasket to whats left of the covers gasket rail.
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Not sure I'd cut an original set of valve cover. There are some other things to consider using the GM finned aluminum covers from the 69. First you already know about the seperators. Next is the dripper tabs that extend down from the ceilings. Third is on my 69Z with original heads, 30/30 cam & stamped GM rockers and valve covers the rockers at each end of the covers were contacting the valve covers due to the radius ends of the cover ceilings. I installed the thickest Fel Pro cork gasket amd gained the cleareance needed to correct. These Motion style covers I use on my crossram car are taller than the GM finned covers, I run a standard thickness gasket, 1.800 installed height Ferea one pc stainless dish, swirl, undercut valves and no clearance issues running stainless full roller rockers. I have run 302 sbc engines to 8K rpm many, many times using stamped steel rockers, with the grooved balls and long slots, (with 3/8 studs). But opted for 7/16 ARP studs & stainless rollers this time. Don't need anything fancy there.
Be careful if using aftermarket heads as many have raised valve cover rails like my BPEs and the covers sit higher than stock and contact the crossram at the lid bolt bosses. This requires careful grinding to correct at all bosses running along the sides/top of the valve covers. But allows removal/installation of covers. Also need valve cover studs vs bolts at least on the upper locations to install the nuts on the studs vs fighting with bolts as there is very limited acess.
180-200 on the seat and 400 full open are really high spring pressures for SBC FT cams. Robert Freand @ Crane suggests 105-125 max on the seat, 330 max full open, 220 min up to 4000 rpm, 260 min above 4000 rpm and screw in studs above 280. My valves are 5.011 L and 1.800 installed ht & with locators and shims 130 on the seat, 325 full open .496" lift FT.
I also run LS beehive Lunati springs on my SBC, much better spring and use the small retainers reducing weight. Both Como Cams & Crane told me they don't know why every SBC FT guy hasn't changed to these.
I will add before installing your crossram base make sure your oil pressure takeoff at rear of engine block is the smallest 90 degree fitting and tight in the block bc once crossram is covering it up you can only tighten it about 90 degrees if it leaks. My future plan is to ditch the tubing with a proper hose assembly.
Final thought to share, not sure what your cam specs are, but don't listen to those telling you the 140 Solid FT cam was designed to be used with the crossram. It was not, it was also intended for a race car that will never see rpms below 4K. It also wasn't a favorite of racers as it had a flat spot in torque around 4K which was where racers were trying to accelerate out of the curves. Chief Engineer Jerry Thompson said in 2022 that cam was simply something he pulled from the GM Heavy Duty parts list and pre-dates the crossram project by many years. There was no funding for racing and he had to get creative saving $$ when he could.
Grumpy Jenkins and David Emanuel both suggest keeping duration at 220@.050 on a crossram for street use. Mine is 224@.050 the intake has a much earlier closing point than the very late closing intake on the 140. So at low engine speeds it isnt bleeding off 2.5 points of compression like the 140. So much more responsive on the street.
